In the sixth physics video lesson from the Academy of Entertaining Sciences, Professor Quark will talk about the law of gravity, as well as another law - the law of universal attraction. These laws affect many phenomena in the world, for example, the shape of our planet, the movement and interaction of bodies. You will learn about the manifestations of these forces and what they depend on by watching a video physics tutorial from the Academy of Entertaining Sciences.
The law of gravity
The law of gravity applies to all bodies on our planet. We owe the discovery of this law to Sir Isaac Newton, the world famous English scientist who lived in the 17th century. According to legend, the idea of \u200b\u200bthe law of gravity came to Newton's mind when he saw an apple falling from a branch. The law of gravity is a special case of another law - the law of universal attraction of objects to each other. According to this law, everything is attracted to everyone. The heavier a thing, the more it attracts surrounding objects to itself. Also, the force of attraction depends on the distance between objects. But why do some objects fall to the ground faster than others? It's about air resistance. So, a sheet of paper falls more slowly than a small pebble because its surface rests on air. Oddly enough, both for light objects and for heavy ones, the force of gravity is the same. Thanks to the law of gravity, people anywhere in the world walk on their feet, and not upside down. After all, the force of gravity acts in the direction of the center of the Earth and it does not matter at what point on the earth's surface we are. By the way, the Earth, other planets and stars owe their form to the force of gravity. This force gives them the shape of a ball, because every planet has a center, to which all the matter of which it consists is attracted. Moreover, it is attracted with the same force. This force depends on the strength of the gravitational field of the planet or star. So, on the Moon, the force of gravity is less and people can move along its surface with huge jumps. This is because the Moon's gravitational field is much weaker than Earth's. The strength of the gravitational field depends on the mass of the planet or star: the greater the mass, the stronger the gravitational field. Thanks to the force of gravity, the planets take their places, revolving in orbits around the Sun.
ABOUT "DROZHALK" AND "PISCHALK"
Tanya was preparing dinner in the kitchen, Irishka was reading a book, and Lena had nothing to do. He walked over to the drafting table. On it lay the bus - long
and a thin ruler for sketching. Lyonya shifted the bus so that one end of it hung over the table, and pulled it - the bus swayed. Lyonya made the end shorter and pulled again - the bus shook faster. Lyonya made the end even shorter, pulled, and how the bus hummed!
Tanya came from the kitchen, went to the table, turned the bus in her hands. Then she put it to the edge of the table, pressed it with her palm and tugged at the tip - the bus hummed.
Well, of course, since it is trembling, it means it is buzzing, - said Tanya. She made the tip shorter, yanked - the flight tire trembled very quickly and hummed in a thin voice. Made the tip longer - the bus shook more slowly and hummed in an angry voice.
Lyonya and Irishka very closely followed what Tanya was doing, finally Lyonya said:
It turns out that the shorter the tip of the bus, the thinner the sound, and the longer the tip, the angrier the sound?
It turns out so, - Tanya agreed. - And here's what you can think of ... Is there a delay?
Yes, - said Lyonya and brought a thin wire. Tanya hooked one end of the wire to the desk drawer and pulled it slightly. After that, she pulled the wire in the middle - the wire hummed. Tanya pulled the wire tighter and pulled again - the wire squeaked thinly. Tanya began to pull the wire harder, sometimes weaker, and this made the wire squeak in a thin or angry voice. Suddenly Irishka ran to the children's room. From there she returned with a violin bow. Irishka began to lead the bow along the wire, and Tanya began to pull the wire harder and sometimes weaker. And everyone heard that they got a song: "Chizhik-fawn, where ... have you ... been? .."
That was what laughter and joy was! And when they calmed down, Tanya said to the children:
Place your fingers lightly on your neck. Now scream!
And the children screamed loudly and loudly. They scream and feel that the throat is trembling.
By the way, you can also do everything that Tanya, Irishka and Lyonya did.
When conducting the experiments described in the story, be sure to draw the child's attention to the fact that only trembling objects sound. The child may ask: why do not all trembling objects sound? For example, if you shake your hand, you will not hear anything. The fact is that our ear hears sound only if the object's vibration frequency is more than 20, but less than 16 thousand vibrations per second. Moreover, the higher the vibration frequency, the higher the sound that we hear. It is necessary to explain to the children that thick "angry" voices are called low. Low voices in bears, hippos, tigers ... The lowest male voice is called bass. The lowest female voice is contralto.
The bus experience can be replaced by the student ruler experience. It is necessary to press the ruler firmly against the table so that the pressed end does not knock on the table when trembling, otherwise this may create a wrong idea in the child about the causes of the sound. It is necessary to ensure that the ruler produces a velvety sound, reminiscent of the sound of a double bass, when played with a pizzicato (pinch).
The experiment with a wire and a bow can be performed without a bow by playing pizzicato on it. In order for the wire to make sounds of different heights, it must be pulled with different strengths. After some practice, you can probably play some simple melodies. It is very important that the children repeat this experience.
MATCH PHONE
One day a fitter came and began to install the telephone. When he finished work, Lenya said, looking at the brand new phone:
We wish we had one!
And to whom did I put this phone? This phone is now yours.
We do not need that, we need our own, so that I can call Irishka from the factory to the hospital.
Where is the hospital and the factory? - asked the fitter. The hospital is on the couch, - said Lyonya, - and the plant is in our room. u
Well, well ... - thought the fitter. - Do you have any matches?
And the threads?
There are threads too.
The electrician put a thread into the needle, then emptied the matches from the box and pierced the bottom of it with the needle. After that, he pulled the thread out of the needle. And to
the end of the thread did not jump out of the box, he tied a match to it. To the second end of the thread, the fitter attached a second matchbox in the same way. When he finished this work, he handed both boxes to the children and said:
You, Irinushka, stay here,
Lyonya, run to your factory.
Irishka took her box and waits, and Lyonya ran to the nursery. There he stopped, and the thread between the boxes was taut like a string. Lyonya put the box to his lips, and Irishka put his to his ear.
Irishka, can you hear me?
I can hear you well even without a telephone.
And you cover the other ear with your hand, - said the fitter.
Irishka covered her other ear with her palm.
Irishka! - Lenya shouted again.
Now you can hear it well on the phone, - said Irishka and put her box to her lips.
Lyonya! .. Oh!
What is "oh"? - asked the fitter.
It tickles your finger, - said Irishka.
What tickles him?
The bottom of the box, - says Irishka.
So it is trembling? asked the fitter.
Yes, - agreed Irishka.
The bottom trembles and makes the thread tremble, - added the fitter.
I know! - Lyonya shouted.
What do you know? - asked the fitter.
A tremor runs along the thread to my box and makes its bottom tremble, and this makes a sound again.
Correctly. Well, when we talk without a match phone, how does the sound of my voice reach your ear? After all, there is no thread, what is trembling?
The children thought. We thought, we thought, and here Irishka says: You know, the air is trembling. Put your fingers to your throat. The fitter attached.
Now say "ah".
Ah-ah-ah, - said the fitter.
Feel your throat trembling?
I feel.
Well, when we speak, the throat trembles, and the air begins to tremble from it, from this the waves run through the air, like through water, only they are not visible in the air, but you can hear them.
Well, well done, - said the mechanic and smiled at the children goodbye.
Make you a telephone out of thread and matchboxes... Talk to someone on this phone, and then touch the thread with your finger. Will they hear you?
Why, if you touch the thread with your finger, the sound does not reach the second box?
When making a toy phone, keep in mind that the thread stretched between the two boxes should not touch any objects, including the fingers that hold the box. It is necessary to explain to the children that if a thread touches an object, then the trembling of the thread is transmitted to this object and does not spread further. Therefore, no sound is heard in the second box.
Instead of matchboxes, you can take any other boxes of suitable sizes: from powder, tooth powder, paper clips. One boy wrote to me that instead of a string, he used a thin wire without soft insulation, forty steps long. He made this experience with friends on the street, and it was very well heard.
You can show children that sound travels not only along a string, but also in other objects. If, while swimming in the river, you lower your head into the water so that your ears are immersed, you can hear the sound of people splashing nearby, a far-off motor of a boat, etc.
Sound propagates well in metals. To verify this, you can knock on the heating battery. In the next apartment, this sound will be heard very well. Of course, you should not abuse this experience, since the sound is transmitted through the pipes not only to the apartment where you need it, but to all other apartments too.
An interesting experience was described in a letter from one girl. Her mother threw a pebble into the water-filled bathtub, and the girl, putting her ear to the wall of the bathtub, listened as waves spreading in circles began to splash against the wall of the bathtub. The result was a visual picture explaining how the sound waves propagate and reach the ear.
It must be borne in mind that in this experience the child will hear the sound of a falling stone twice. First, he will hear a sound that was transmitted using sound waves, which in water, as well as in air, are invisible and propagate at great speed. Then the child will see ordinary waves on the surface of the water, which spread in circles in all directions from the place of fall, and, finally, when these waves reach the wall of the bath, he will hear them. You need to explain to the child that real sound waves in water, as well as in air, are not visible, and you did the experiment with waves on the surface of the water in order to better understand how sound propagates in all directions in air, in water and other substances.
HOW TO MAKE SOUND LOUDER
One day Lenya invented a new "trembling". It was a hairbrush. You pull the clove, and the comb will squeak. Only it was painfully quiet. He brought Lenya the comb to his ear, now you can hear it well and loudly, but the trouble is: Lenya hears well, but Irishka, who draws at the table, does not hear at all. I put Lenya comb to his forehead, again only he hears well. Finally, I thought to put the comb to the table. I pulled a clove, and the comb clinks loudly. Irishka looks up from the drawing and looks at what Lenya is doing. And Lyonya, let's put the comb to everything that falls into the eye: to the window, to the door, to the piano ... And every time he puts the comb to a solid object, the comb squeaks loudly, but as it lifts it into the air, it squeaks weakly.
Tanya also took an interest in this discovery. She rolled a megaphone from a sheet of paper and says to Lena:
Put the hairbrush on the horn.
Lenya put the comb to the horn, pulled the tooth, and the comb squeaked loudly.
Why is it louder with a horn? - asked Tanya.
Children don't know.
Here is Tanya and says:
When a clove trembles, it sways the air around itself, but the clove is small and does not sway enough air, so the sound is quiet.
Then Irishka said:
When we put the comb to the horn and pulled on the clove, the horn also trembled, but it is large and sways a lot of air, so the sound turns out louder.
Well, and the table trembles when we put a comb to it? - asked Lenya.
Put your finger on the table, - asked Tanya.
Lyonya put it in, and Tanya put a comb next to it.
fnula Tanya for a clove and asks:
Well? Is the table trembling or not?
Shivers a little! - Leon was surprised.
Irishka, of course, immediately began to explain:
Although the table trembled weakly from the comb, it is large and it sways much more air than the tooth of the comb, so the sound is loud.
After everyone understood why the sound is loud, the children took a stick and nailed a clove at the ends. A wire was pulled over the studs, to the lower end of which a horn was attached. Tanya brought a violin bow, gave it to Irishka and says:
The result is an amazing cello.
Tanya sat at the piano; Irishka took the bow in her hand, and with the fingers of her other hand began to press the wire-string; Lyonya held the megaphone so that it would not fall to the floor. And all together began to play the song "Chizhik-Pyzhik". The sound of a homemade cello is like the roar of a hungry bear woken up in winter. The cello roars, but still it turns out well - loud and funny!
AUTHOR
that book is the result of work on a series of television programs "Physics for Kids", created on Novosibirsk television. The programs aroused great interest among children and parents. I received from them a lot of letters with answers to tasks, with stories about the experiments and observations that the children carried out on their own initiative, with questions that had to be answered in the next program. I am not a physicist by profession, but a cameraman, but an interest in physics and a passion for it appeared in my childhood. I owe this to my father, who taught me everything that is described in this book. The book is not a textbook. This is a popular exposition of some of the issues studied by the science of physics. "Physics for Toddlers" can be read in a family with older preschoolers and junior schoolchildren, and also use for classes in kindergarten and for extracurricular activities at school.
The main goal of the book is to show children that the world around them is cognizable, that all natural phenomena can be scientifically explained. Reading a book should encourage the child to make independent observations and experiments, to play games similar to those in which the heroes of the book are engaged.
You should not read the book "voraciously", from such reading there will be little benefit. It is best to read one story at a time, since each
This story introduces complex physical phenomena that are not always easy for kids to understand. After reading, be sure to help your child carry out the experiments and observations described in the story, ask questions and discuss the answers to them with the child. This will help the child to assimilate the knowledge gained and will contribute to the development of his logical thinking, curiosity and ingenuity.
All experiments should be carried out by children under adult supervision. This is necessary, firstly, for the successful and correct conduct of experiments, and secondly, for compliance with the rules of "safety measures". Adults should be especially attentive to the experiments described in the sections: "Light phenomena", "Inertia and jet motion", "Electricity and magnetism". Getting to know physics should be enjoyable and enjoyable. Therefore, there is no need to force a child to study in those cases when he is not disposed to study physics. Lessons with a book should not be likened to a school lesson. The more relaxed the game will be
the "experiences" the better for the case. In the stories for reading, a lot of secondary information is deliberately omitted in order not to clutter up the main idea of \u200b\u200bthe story with an abundance of facts and to help the child understand the very essence of the phenomena. Therefore, after each story, detailed comments are printed. Here adults can find some tips on experimental techniques and brush up on physics knowledge. For those who have studied physics for a long time and are not familiar with it, this material may not be enough. In this case, we advise you to refer to school physics textbooks. When working with the book, proceed from your experience and the relationship with your children. You know your little ones better. They are used to you and your way of communicating with them.
THE MAIN THING IS A CREATIVE APPROACH TO THE BUSINESS AND RESPECT FOR THE INNER WORLD OF THE CHILD.
I sincerely wish you success!
ABOUT "DROZHALK" AND "PISCHALK"
Tanya was preparing dinner in the kitchen, Irishka was reading a book, and Lena had nothing to do. He walked over to the drafting table. On it lay the bus - long
and a thin ruler for sketching. Lyonya pushed the rail so that one end of it hung over the table, and pulled it - the rail swayed. Lyonya made the end shorter and pulled again - the bus shook faster. Lyonya made the end even shorter, pulled, and how the bus hummed!
Tanya came from the kitchen, went to the table, turned the bus in her hands. Then she put it to the edge of the table, pressed it with her palm and tugged at the tip - the bus hummed.
- Well, of course, since it is trembling, it means it is buzzing, - said Tanya. She made the tip shorter, yanked - the flight tire trembled very quickly and hummed in a thin voice. Made the tip longer - the bus shook more slowly and hummed in an angry voice.
Lyonya and Irishka very closely followed what Tanya was doing, finally Lyonya said:
- It turns out that the shorter the tip of the flight tire, the thinner the sound, and the longer the tip, the more angry the sound?
- It turns out so, - agreed Tanya. - And here's what you can think of ... Is there a delay?
- Yes, - said Lenya and brought a thin wire. Tanya hooked one end of the wire to the desk drawer and pulled it slightly. After that, she pulled the wire in the middle - the wire hummed. Tanya pulled the wire tighter and pulled again - the wire squeaked thinly. Tanya began to pull the wire harder, sometimes weaker, and this made the wire squeak in a thin or angry voice. Suddenly Irishka ran to the children's room. From there she returned with a violin bow. Irishka began to lead the bow along the wire, and Tanya began to pull the wire harder and sometimes weaker. And everyone heard that they got a song: "Chizhik-fawn, where ... have you ... been? .."
That was what laughter and joy was! And when they calmed down, Tanya said to the children:
- Place your fingers lightly on your neck. Now scream!
And the children screamed loudly and loudly. They scream and feel that the throat is trembling.
By the way, you can also do everything that Tanya, Irishka and Lyonya did.
When conducting the experiments described in the story, be sure to draw the child's attention to the fact that only trembling objects sound. The child may ask: why do not all trembling objects sound? For example, if you shake your hand, you will not hear anything. The fact is that our ear hears sound only if the object's vibration frequency is more than 20, but less than 16 thousand vibrations per second. Moreover, the higher the vibration frequency, the higher the sound that we hear. It is necessary to explain to the children that thick "angry" voices are called low. Low voices in bears, hippos, tigers ... The lowest male voice is called bass. The lowest female voice is contralto.
Thin voices are called high voices. High voices in mice, birds, hares ... The highest female voice is called a soprano, the highest male voice is a tenor.
The bus experience can be replaced by the student ruler experience. It is necessary to press the ruler firmly against the table so that the pressed end does not knock on the table when trembling, otherwise this may create a wrong idea in the child about the causes of the sound. It is necessary to ensure that the ruler produces a velvety sound, reminiscent of the sound of a double bass when pizzicato is played on it (by pinching).
The experiment with a wire and a bow can be performed without a bow by playing pizzicato on it. In order for the wire to make sounds of different heights, it must be pulled with different strengths. After some practice, you can probably play some simple melodies. It is very important that the children repeat this experience.
MATCH PHONE
One day a fitter came and began to install the telephone. When he finished work, Lenya said, looking at the brand new phone:
We wish we had one!
And to whom did I put this phone? This phone is now yours.
We do not need that, we need our own, so that I can call Irishka from the factory to the hospital.
Where is the hospital and the factory? - asked the fitter. The hospital is on the couch, - said Lyonya, - and the plant is in our room. u
Well, well ... - thought the fitter. - Do you have any matches?
There is!
- And the threads?
- There are threads too.
- Get it!
The electrician put a thread into the needle, then emptied the matches from the box and pierced the bottom of it with the needle. After that, he pulled the thread out of the needle. And to
the end of the thread did not jump out of the box, he tied a match to it. To the second end of the thread, the fitter attached a second matchbox in the same way. When he finished this work, he handed both boxes to the children and said:
- You, Irinushka, stay here,
Lyonya, run to your factory.
Irishka took her box and waits, and Lyonya ran to the nursery. There he stopped, and the thread between the boxes was taut like a string. Lyonya put the box to his lips, and Irishka put his to his ear.
Irishka, can you hear me?
I can hear you well even without a telephone.
And you cover the other ear with your hand, - said the fitter.
Irishka covered her other ear with her palm.
Irishka! - Lenya shouted again.
Now you can hear it well on the phone, - said Irishka and put her box to her lips.
Lyonya! .. Oh!
What is "oh"? asked the fitter.
It tickles your finger, - said Irishka.
What tickles him?
The bottom of the box, - says Irishka.
So it is trembling? asked the fitter.
Yes, - agreed Irishka.
The bottom trembles and makes the thread tremble, - added the fitter.
I know! - Lyonya shouted.
What do you know? - asked the fitter.
A tremor runs along the thread to my box and makes its bottom tremble, and this makes a sound again.
Correctly. Well, when we talk without a match phone, how does the sound of my voice reach your ear? After all, there is no thread, what is trembling?
The children thought. We thought, we thought, here Irishka says: You know, the air is trembling. Put your fingers to your throat. The fitter attached.
Now say "ah".
Ah-ah-ah, - said the fitter.
Feel your throat trembling?
I feel.
Well, when we speak, the throat trembles, and the air begins to tremble from it, from this the waves run through the air, like water, only they are not visible in the air, but you can hear them.
Well, well done, - said the mechanic and smiled at the children goodbye.
Make a telephone out of string and matchboxes too. Talk to someone on this phone, and then put your finger on the thread. Will they hear you?
Why, if you touch the thread with your finger, the sound does not reach the second box?
When making a toy phone, you need to keep in mind that the thread stretched between two boxes should not touch any objects, including the fingers that hold the box. It is necessary to explain to the children that if a thread touches an object, then the trembling of the thread is transmitted to this object and does not spread further. Therefore, no sound is heard in the second box.
Instead of matchboxes, you can take any other boxes of suitable sizes: from powder, tooth powder, paper clips. One boy wrote to me that instead of a string, he used a thin wire without soft insulation, forty steps long. He made this experience with friends on the street, and it was very well heard.
You can show children that sound travels not only along a string, but also in other objects. If, while swimming in the river, you lower your head into the water so that your ears are immersed, you can hear the sound of people splashing nearby, a motor boat running far away, etc.
Sound propagates well in metals. To verify this, you can knock on the heating battery. In the next apartment, this sound will be heard very well. Of course, you should not abuse this experience, since the sound is transmitted through the pipes not only to the apartment where you need it, but to all other apartments too.
An interesting experience was described in a letter from one girl. Her mother threw a pebble into the bathtub filled with water, and the girl, putting her ear to the wall of the bath, listened to the waves spreading out in circles and splashing against the wall of the bath. The result was a visual picture explaining how the sound waves propagate and reach the ear.
It must be borne in mind that in this experience the child will hear the sound of a falling stone twice. First, he hears a sound that was transmitted using sound waves, which in water, as well as in air, are invisible and propagate with great speed. Then the child will see ordinary waves on the surface of the water, which spread in circles in all directions from the place of fall, and, finally, when these waves reach the wall of the bath, he will hear them. You need to explain to the child that real sound waves in water, as well as in air, are not visible, and you did the experiment with waves on the surface of the water in order to better understand how sound propagates in all directions in air, in water and other substances.
HOW TO MAKE SOUND LOUDER
One day Lenya invented a new "trembling". It was a hairbrush. You pull the clove, and the comb will squeak. Only it was painfully quiet. He brought Lenya the comb to his ear, now you can hear it well and loudly, but here's the trouble: Lenya hears well, but Irishka, who draws at the table, does not hear at all. I put Lenya comb to his forehead, again only he hears well. Finally, I thought of putting a hairbrush on the table. I pulled a clove, and the comb clinks loudly. Irishka looks up from the drawing and looks at what Lenya is doing. And Lyonya, let’s put the comb to everything that falls into our eyes: to the window, to the door, to the piano ... And every time he puts the comb to a solid object, the comb squeaks loudly, but as it lifts it into the air, it squeaks weakly.
Tanya became interested in this discovery. She rolled a megaphone from a sheet of paper and says to Lena:
Put the hairbrush on the horn.
Lenya put the comb to the speaker, pulled the tooth, and the comb squeaked loudly.
Wow! - said the children in one voice.
- Why is it louder with a mouthpiece? - asked Tanya.
Children don't know.
Here is Tanya and says:
When a clove trembles, it sways the air around itself, but the clove is small and does not sway enough air, so the sound is quiet.
Then Irishka said:
- When we put the comb to the horn and pulled the tooth, the horn also trembled, but it is big and it sways a lot of air, so the sound turns out louder.
- Well, and the table trembles when we put a comb to it? - asked Lenya.
“Put your finger on the table,” Tanya asked.
Lyonya put it in, and Tanya put a comb next to it.
fnula Tanya for a clove and asks:
- Well? Is the table trembling or not?
- A little trembling! - Leon was surprised.
Irishka, of course, immediately began to explain:
- Although the table trembled weakly from the comb, it is large and the air sways much more than the tooth of the comb, so the sound is loud.
After everyone understood why the sound was loud, the children took a stick and nailed a clove at the ends. A wire was pulled over the studs, to the lower end of which a horn was attached. Tanya brought a violin bow, gave it to Irishka and said:
- We got an amazing cello.
Tanya sat at the piano; Irishka took the bow in her hand, and with the fingers of her other hand began to press the wire-string; Lyonya held the megaphone so that it would not fall to the floor. And all together began to play the song "Chizhik-Pyzhik". The sound of a homemade cello is like the roar of a hungry bear woken up in winter. The cello roars, but still it turns out well - loud and funny!
In order to make a cello, it is best to take a simple stick, round or rectangular in cross section. The thickness of this stick should be such that a child can easily grasp it with his fingers, like a guitarist grabs the neck of a guitar. A small nail should be nailed to the upper end of the stick, and a steel wire 0.5 - 1 mm thick should be tied to it. It is better to take one of the bass (braided) strings of the guitar for this purpose. A second nail must be nailed to the lower end of the stick and the second end of the wire must be tied to it after tension. While pulling on the wire, you need to tug lightly with your fingers all the time, achieving a low, velvet tone. After the string is stretched, at a distance of no more than 5 mm from the lower stud, a paper horn should be strengthened with a needle. The most suitable material for him is whatman paper or cardboard. It is best to roll up a large megaphone from a full sheet of Whatman paper. The wide end of the horn should be tied to the top end of the stick. You can play such a "cello" with a bow and pizzicato. In order to prevent the string from touching the stick during the game, you should put a match near the nails or make a ring of thick wire around the stick in the same places. If you have a piano, button accordion, guitar, or any other musical instrument, try playing the VioDoncel with accompaniment.
Several more musical "instruments" can be made with the children.
Place several (seven to ten) wine glasses, glasses or glasses on the table (better not cut, but smooth) and pour different amounts of water into them. When pouring water into a glass, tap the edge with a pencil. At the same time, you can hear that, as the glasses are filled with water, the sound becomes lower. You just need to make sure that there are no air bubbles on the walls of the glass, as they make the sound dull and inexpressive. These bubbles can be easily removed by sliding your finger along the wall of the glass, and so that they do not appear, it is better to pour warm boiled water. Using a piano, button accordion, children's xylophone, or just by ear tune the glasses to a scale, for example, in C major, and try to play something on such an unusual "instrument".
Dry pine sticks can be used to make a good xylophone. To make the sticks sound better, place them on two folded cardboard strips. The sticks are adjusted like this: if you need to increase the sound, the stick is shortened by cutting it off from the end; if the sound needs to be lowered, the stick is made a little thinner in the middle. Such a xylophone is played with a wooden mallet attached to a thin handle. You need to hit not hard, but sharply so that the hammer instantly bounces up.
You can fasten two thick pieces of metal, plexiglass or textolite (4 - 5 mm thick) with bolts and clamp thin wooden student rulers between them. By adjusting the rulers with the piano, we get a kind of "contrabass". "Contrabass" must be firmly pressed against the table, the lid of which in this case plays the role of a resonator that amplifies the sound.
WHY DOES THE HARE NEED LONG EARS
Children walked in the forest. They looked, the boy was standing, he put the horns to his ears, supported them with his hands, listened. The children asked the boy for mouthpieces and began to listen to the sounds of the forest. Sunny day, the birds are singing, the bees are buzzing,
mara - interesting. You can hear a dog barking, although it's far from the village, but a cow moaning. Noisy and loud in the forest, you can hear frogs croaking in the swamp, the engine hums in the distance
tractor. And you remove the horns, and immediately there is silence,
as if deaf, a birdie screams directly over his head, and nothing else is heard. The guys liked these mouthpieces.
They also made them from large sheets of cardboard, and so that they would not wrinkle, they sewed them onto the edges along a plastic hoop. We came to the forest. Irishka put her mouthpiece on, and Lyonya picked up his own and ran to the other side of the clearing. The glade is large, Lyonya ran three hundred paces and stopped, put his lips to the megaphone and how he screamed:
Irishka-ah !!!
Irishka bounced aside from her speaker, it seemed to her that Lenya had shouted right into her ear.
Irishka speaks into her megaphone quietly, in a whisper:
Lyonya, speak quietly.
Lyonya listens to Irishka, and it seems to him that she is whispering right in his ear. Lyonya understood that one didn't need to shout into such horns, and quietly replies to Irishka:
Good.
Irishka got ready to say something else to Lena, but at that time in the sky something crashed and cracked so that it became clear even without the horns that it was thunder. We all looked at the sky, and there was a huge cloud and the sun was already hiding behind it.
Lyonya, run here! - Tanya shouted and hid with Irishka under a tree. As soon as Lyonya came running, a terrible downpour gushed out. It was pouring around like a bucket, but Lena felt thirsty, so much so that he could not bear it, jumped out into the rain, opened his mouth and caught the drops - he wants to get drunk. Tanya laughed, took out a folding travel glass, put it on the grass. Of course, more drops will get into the glass than into the open
mouth, but still not enough, the water will take a long time to collect. And then Irishka guessed what to do. She grabbed her huge horn, turned the wide end up, and held the narrow end over the glass. A lot of rain drops at once into the wide end of the horn, and they all flow down into the narrow end, so water runs from the horn into the glass, as if from a water main. Lenya got drunk, and Tanya says:
Well done, Irishka! Well, who understood why you can hear better through a megaphone?
The horn has one wide end, - says Irishka. - A lot of sound gets into it, and all of it collects in the ear, well, like in a funnel.
So the ears of a hare are also two horns? - asked Lenya.
Well yes! - Irishka answered cheerfully.
And then the rain ended.
It is best to experiment with horns outside the city, in the forest or in the field. To prevent large horns from crushing, at their wide end, they must be reinforced with a gymnastic hoop. If, in a field or in a forest, two such horns are spread at a distance of 150-200 m, then one can talk with their help in a whisper. Needless to say, how such (or smaller) horns can be useful in childish games, for example, in "detectives" and "robbers"!
If you have a thin rubber tube, cut off two pieces, insert them into the narrow end of the horn, wrap them with insulating tape, and insert the free ends of the tubes into both ears. With such a simple adaptation, distant sounds are heard much better.
HOW TO SEE YOUR VOICE
Once Lenya rushed home with a shout:
Look what they gave me at the construction site! - in his hands he held several strips of glass, wrapped in paper so as not to cut his hands. Lyonya put the glasses on the table, everyone gathered and began to think what could be made of this glass. Suddenly Tanya says:
- I think I know. You, Lyonya, carry a tin can and a key, and you, Irishka, paper and glue. Lenya brought a tin can
ku without a lid, and Tanya cut out the bottom with a key. The result is a wide and short tin tube. After that, Tanya cut out a circle of thin paper and glued it instead of the bottom. When the glue dried, Tanya sprinkled the paper with water. I pierced two holes with a nail in the walls of the can and inserted a thick wire in the shape of the letter P into these holes. By this time, the paper bottom, moistened with water, had dried and stretched like on a drum. Tanya dripped
A drop of clerical glue in the middle of a piece of paper quickly put a narrow strip of tin with a pointed tip, like a bent needle, to this drop and left it to dry.
Then Tanya lit a candle and began to drive a strip of glass over the flame. Soon the glass turned black with soot.
Tanya put the strip on the table with the smoked side up and put the tin can so that the tin needle touched the smoked glass with its tip.
- So what? - asked Lenya, looking at this strange car.
- And that's what, - said Tanya, - now I will pull the glass strip, and you scream. Prepared ... - Tanya quickly pulled a strip of glass, and Lenya would scream:
- Ta-anya-I-I!
Tanya picked up a strip of glass and turned it towards the light. The sharpened tin scratched a transparent line on the smoked glass. At first, the line was straight, and from the middle it became wavy.
- Well, here, - said Tanya, - while Lenya was silent, the line was even, but when he screamed, it became wavy. Why?
- And I know, - said Irishka, - when Lyonya screamed, the piece of paper trembled from the scream and the tin needle trembled and the line turned out with convolutions.
Lyonya took a strip of glass and looked at it too.
“So my voice is drawn here? - he asked.
- Well yes! - Tanya laughed.
- Let's draw your voices too, - suggested Lenya.
- Come on, - agreed Tanya and Irishka.
They put the glass on the table, put the tip of a tin needle on the smoked glass. Tanya pulled the strip, and Irishka would scream:
- Lyo-yonya-I-I !!!
- Now you, - said the children to Tanya.
Tanya went to the bank, got ready. Irishka pulled a strip of glass, Tanya shouted:
- I-ira-ah !!!
Look at the drawing of the smoked glass. See the three fibrous lines? They are all different, because on the top it is written: "Tanya", on the middle - "Lenya", and on the bottom - "Ira". Take a closer look at these drawings, read the story again and try to record your own voice on the smoked glass using a tin can, a stretched paper bottom, and a tin needle.
A device for recording sound on smoked glass is not easy to make, but the result you achieve will justify all the efforts.
The general structure of the sound recording device is clear from the figure.
A membrane made from a piece of paper can be glued to a metal can using office glue. Instead of a regular tin can, you can take a cardboard jar (for example, from powder) or just glue it from cardboard or thick paper. The needle, or rather a narrow strip of tin, is glued to the membrane with clerical glue and small additional pieces of paper. It is very important that the membrane is well stretched before gluing the needle, for this it must be sprinkled with water and allowed to dry.
In order for the needle to follow exactly the vibrations of the membrane, it is necessary to give the shape shown in the figure.
For recording to be successful, the pressure of the needle on the glass must be minimal. To achieve this, you need to balance the jar by attaching pieces of plasticine to the opposite edge of it.
Since you have to scream quite loudly to record the sound, the pitch will be large. Let us assume, approximately, that the oscillation frequency is 600 oscillations per second. This means that if you move the glass strip at a speed of 600 mm / s, then the length of one wave in the record will be 1 mm. Although 600 mm / sec is a low speed, on one track we will not have time, of course, to record anything but a short cry. If you still have a gramophone or gramophone (with mechanical sound reproduction), then you can do the following: install the needle on the last, non-spiral track of the record and shout loudly into the gramophone pipe or into the wide hole on the upper side of the gramophone box, after which you will hear a faint squeak - recording the sound of your voice on a disc. Discuss with your child how the recording came about.
WHY PLATE SINGS
The turntable once went bad, and Irishka needs to listen to the records. She sits, pouting her lips. Here is Tanya and says to her:
- Look at the plate through the magnifying glass. Irishka took the plate and examines it through a magnifying glass.
Tanya asks:
- Do you see the small grooves?
- I see.
- What are they, straight
or with convolutions?
- With convolutions, - Irishka answers.
- Well, and the needle runs smoothly along the wavy groove or
begins to tremble?
- Probably trembling.
- And since it is trembling, it means ...
- Beeps ... - Irishka smiled.
Tanya took a paper horn, stuck a sewing needle into the tip. Then she put the record on the pencil.
I'll spin the record, and you hold the megaphone.
Tanya twists the pencil, and the record is spinning on the pencil. Irishka took the megaphone and put the needle on the plate, and the plate as she sings: “You, titmouse, where have you been? Where did you make a nest? ... "
It is difficult to twist the record evenly, it turns faster, then slower, and therefore the song sounds funny - now thin, like Pinocchio, now in bass, like a bear. Irishka, when she heard such funny sounds, began to laugh, immediately the mood improved.
Make an experiment with a record, pencil and horn with a needle. Try spinning the record at different speeds. Why does the sound of Zhg turn out to be high or low?
The experience with playing a record is very simple. It is only important not to forget that in this way it is possible to play ordinary short-playing records without harm. LPs are easily damaged by a sewing needle or safety pin. In addition, the width of the sound groove of the LP is small, and the sewing needle is installed on two grooves at once. In order for the horn to easily and freely follow along with the needle along the sound track, you must hold it by the very edge at the top. If the plate is rotated on a pencil, it is very difficult to achieve uniform rotation and the sound "floats". The same experiment can be done by rotating the record on the turntable disc, but reproducing the sound as before with a needle and a horn.
HOW TO AUCHNE, SO AND RESPOND
It was a hot sunny day. Irishka jumped over the rope, and Lyonya watched. Irishka jumped, jumped, and got lost, probably because it was very hot.
- Lost, lost! - Lyonya shouted. Irishka is offended, she says:
Let's go, I'll show you something ... The children ran under the arch that was in their house. They ran up and stopped. Irishka prepared herself and shouted:
AND!!! - shortly like this: - A !!!
And someone from above responds:
AND! - a little quieter, but in Irishka's voice.
Who is it? - asked Lenya.
Echo.
AND!!! - Lenya shouted just as loudly and shortly.
Why are you yelling here?
The children turned around and saw Uncle Misha, an old man with a wide beard, as in the old days. Uncle Misha was famous
in the yard like an avid angler. His voice was angry, but his face was kind.
“We’re not yelling,” says Lyonya, “there is an echo, it’s yelling.
- AND!!! - shouted Uncle Misha, and from above the echo of Uncle Misha's voice:
- AND!
- Is this an echo? - says Uncle Misha. - Tell Tanya to let you go fishing with me, there I will show you an echo!
Tanya let go. Not right away, of course ...
It was cooler on the river than in the city, and therefore everyone was in a better mood. Uncle Misha placed his fishing rods and got ready to doze, as all anglers do.
- And where is the old man? - asked Lenya.
Uncle Misha even shuddered:
- What old man?
- Well, that Echo.
“Oh, echo,” Uncle Misha recalled. - AND!!!
Uncle Misha shouted, but no one responded, no matter how much the guys listened. Lyonya was about to ask again about the old man Echo, when suddenly from afar someone from Uncle Mishin answered in a voice:
- AND!
- Why is he responding? - Leon was surprised.
- Oh, you don't know, - said Irishka, took a stone, threw it into the water. The rock flopped down, and waves emanated from it in all directions. The waves reached the shore and began to bounce in the opposite direction.
You have probably already guessed that the waves on the water and the sound in the air are a bit alike.
Lenya also understood this.
“When I shout,” he said, “the air begins to tremble. This tremor runs in all directions. She will run to the shore, knock and come back, right in my ear.
- That's right, - says Uncle Misha, - otherwise - an old man!
- And I was joking about the old man, because I didn't know, - Lyonya answered.
It is necessary to draw the child's attention to the fact that the echo - the reflected sound - is heard not immediately, but after a while. This is because sound does not travel instantly through the air, but at a speed of 340 m / s. For comparison, we can say that passenger jets fly 2 times slower than sound, and military ones - faster than sound.
Another interesting fact: as you know, thunder is the sound of an electrical discharge - lightning. Why lightning flashes almost instantly, and thunder rumbles are heard for a very long time and not simultaneously with lightning? The lag of thunder is explained by the fact that the speed of sound is a million times less than the speed of light. We see light almost simultaneously with an electric discharge (the speed of light is 300,000 km / sec), and sound takes several seconds to reach the observer. If immediately after a flash of lightning you start counting seconds (zero, and-times, and-two, and-three, etc.); then it is possible, by multiplying the time from the moment of the flash to the first roll of thunder by the speed of sound, to obtain the distance to the place of the electric discharge. Now it is not difficult to understand why the thunderclaps are heard for a long time. Lightning is often several kilometers long. From those areas of lightning that were located closer to us, we will hear the sound first. From the most distant parts of the lightning, the sound will reach after a few seconds. In addition, for some time we will hear echoes reflected from clouds and large terrestrial objects (mountains, large forests, etc.).
Using the properties of sound to propagate at a relatively low speed, it is possible to determine the distance to inaccessible objects using echo. To do this, you need to shout shortly but loudly and notice the time between the shout and the echo. Since the sound has passed the distance from you to the object twice, this time must be divided by two and then multiplied by the speed of sound. For example, it took 3 seconds from the moment you shouted until the echo returned. Since the path of sound to the object is half the total path that it has traveled, we divide 3 seconds by two, we get 1.5 seconds. Multiplying this time by the speed of sound (340 m / s), we get the distance to the object - 510 m.
The operation of echo sounders is based on this principle - special devices for determining the depth of the sea. The echo sounder emits a strong, short beep and then catches the echoes reflected from the seabed. By multiplying the speed of sound in water by the time between the signal and the moment the echo returns and dividing this value in half, the distance dfdn is found. The depth of the sea sometimes exceeds 10 km, and it is impossible to measure this depth with an ordinary lot (a load tied to a rope).
QUESTIONS B ASSIGNMENTS
1. Why does a mosquito squeak while it flies, and when it sits down, it stops talking?
2. Which animals and birds have high (thin) voices, and which ones - low (angry)?
Why do mosquitoes squeak thin (high), and bumblebees, wasps and bees buzz in a bass (low)?
4. What is your voice (high or low)? Daddy's? Mom? By Grandma?
5. How is the wire stretched (strong or weak) when it beeps thin (high)? When does it sound bass (low)?
6. If you have a metallophone or xylophone, pay attention to which records are high-pitched, short or long ones?
7. Why are many wind musical instruments - horns, trumpets, trombones, tubas - made in the form of horns? Where else have you met mouthpieces?
8. Why is a beautiful box with a hole made of plywood from a guitar, violin, cello, mandolin, balalaika and other stringed musical instruments? Try to knock softly first on the table or on the wall, and then on the box of the stringed instrument. When is the sound louder?
Make a "cello" from a stick, a wire and a horn, play on it, pressing the string to the stick with your finger, and then tell me why if you press the string down, the sound is high (thin), and if you press the string at the top, the sound is low (angry )?
9. Make a device to record voice on a smoked glass or iron ruler. Try to record your voice, and then answer how you can record the voices of people and musical instruments on records.
Make an experiment with a record, a pencil and a horn and a needle. Try spinning the record at different speeds. When is the sound of the record like Pinocchio's voice, and when - like the voice of a bear? Why does this happen?
12. At the construction site, you can see thick and long pipes made of concrete, iron or fired clay. If you sit down at one end of the pipe and say something in a whisper, then at the other end of the pipe the sound will be heard clearly and loudly. Why does this happen?
13. Why in a completely empty room (when you move to a new apartment or during renovation) you can hear the echo very well? Why, when things are brought into the room, curtains and carpets are hung, the echo becomes quieter and then completely disappears?
Experiments with sunbeams usually captivate children. Very interesting experiments can be carried out on a sunny morning, when a light morning fog hangs in the air. Rays of light can be easily observed in this fog. Strictly speaking, we see not the rays of light themselves, but particles of fog suspended in the air and illuminated by the sun. But it will not be too much of a mistake if we talk about the rays of light that we see in fog or haze. A ray of light in the haze is especially clearly visible if it is directed towards us. If on a sunny and slightly foggy morning you direct a beam of light at the child with a mirror, but not directly into the eyes, but so that the "bunny" is not far from the face, then the child will clearly see how a bright ray stretches from the mirror to him. This experience looks very beautiful if the light is reflected not from a mirror, but from the swaying surface of a river or pond. In this case, beautiful rays of light running through the air are visible, reflected from the water. This experience should also be performed while facing the sun and reflected rays.
At home, these experiences can be significantly changed if you have an aquarium and a conventional filmscope. Instead of a film strip, a piece of black paper with a hole of 3 to 5 mm in diameter should be inserted into the filmoscope frame. If you now turn on the filmoscope, a thin and bright beam of light extends from it. By aiming it at the aquarium, you can clearly see this beam. A little muddy water plays the role of fog here. If a mirror is placed in the path of the light beam in the water, it will be very clearly visible how, reflected from the mirror, the beam will change its direction. Of course, it is best to carry out these experiments in the evening in complete darkness.
MIRROR FOCUS
Lined up in a row, the Indians showered arrows from their bows on the pale-faced, who were playing leapfrog and did not expect an attack. But after a few moments, when the pale-faced had time to hide behind a pile of firewood, in the attic of the barn and behind the old sleigh that stood in the very corner of the yard, and when they opened fire from their weapons, the Indians had a hard time. Day by day, the pale-faced more and more sharply watched the surroundings, posted sentries everywhere. As soon as the head with a feather on top of the head appeared from around the corner of the shed, a shot and a cry: "Fall!" And I had to fall, these are the rules of this game.
But one day, when, it seemed, the Indians were already defeated, Hawkeye came up with this. To avoid being shot, he did not put his head around the corner of the shed, but a mirror, in which he could see everything that the pale-faced were doing. The Indians waited until the pale-faced sentries were distracted, and with a warlike cry rushed from ambush at their enemies. Once the Indians hid behind a high fence, in which there was not a single crack. Hawkeye took out his mirror, lifted it above his head, but could not reach the top of the fence. But it was not for nothing that the Indians were considered cunning and resourceful. Hawkeye looked around and found a wand with a fork at the end. He attached the mirror to the fork with a piece of plasticine and raised it over the fence. Now the pale-faced sentry was visible in the mirror, but only standing with his head up was uncomfortable.
“Give me a minute,” Black Panther asked for his wand. She took her mirror and placed it on the lower end of the
lochki. The upper mirror is visible in the lower mirror, and the white-faced sentry is visible in the upper mirror. The Indians did not know that they had invented a device called the periscope.
The periscope is used in submarines. She swims under water, and the periscope looks out of the water a little. The captain looks through the periscope and clearly sees everything that is done at sea. Only briefly did the Indians look through their periscope. Pale-faced Vaska noticed a mirror over the fence, leaned out from behind a bush, a slingshot bang - there is no mirror. Crashed to smithereens! The trial over Vaska was harsh! Everyone judged - both the pale-faced and the Indians, because everyone feels sorry for a good thing.
- Give it to the dirty jackals! shouted Hawkeye.
- Shame on the pale-faced!
- Let him make a new periscope!
Soon Vaska realized that you couldn't get off that way, and promised to make a new periscope by morning. The next morning, when Tanya was going for milk, she saw a sad Vaska. He twisted three strips of glass in his hands and did not know what to do with them. He told Tanya about his misfortune, and they began to think together. Vasya folded three strips of glass like the roof of a house. It turned out to be such a triangular tube. Looked
he into this tube and smiled sadly.
Tanya also looked - she was delighted. Because Vasya accidentally invented new toycalled a kaleidoscope. Vasya and Tanya began to look at houses, flowers, butterflies and just pieces of glass through a kaleidoscope. Look at the pictures. This is what Tanya and Vasya saw through the kaleidoscope.
See what a funny toy you came up with. The guys will be delighted, ”Tanya said to Vasya.
But what about the periscope?
Tanya went to the store and bought two brand new periscopes - for the Indians and the pale-faced.
Only now there are no Indians or pale-faced people in the village, but there are simply detectives and robbers.
From the pictures, you can easily understand the structure of the periscope and kaleidoscope and how to carry out several experiments with mirrors.
How to fry an egg in the sun
Irishka was sitting on the porch and reading to the children:
- Once, the ancient Roman ships approached the ancient Greek city of Syracuse and laid siege to the city. Then a scientist named Archimedes summoned the citizens of Syracuse to the shore, gave them a mirror and ordered the bunnies from the mirrors to be sent to one of the Roman ships. There was so much light and heat from the mirrors that the ship caught fire.
The children liked the story about the Roman navy and the mirrors of Archimedes. They sat down at the gate and directed the bunnies from the mirrors to the stack of firewood. Since there were many children and there were also many bunnies, one log began to smoke from the light and heat.
- Enough, otherwise it will catch fire, - said Irishka.
- We need to fry a little more, - Lyonya answered, and at that moment a cheerful tongue of flame flared up on the cut of the log. The children scattered all over the place. And only Irishka ran to call the fire brigade.
A minute later, a fire engine was racing through the streets. Firefighters arrived on time. The fire was soon extinguished.
Who did this? - asked the Chief Fireman. - I ask: who did it?
We, - Irishka answered for everyone. The fireman paused and asked again:
Who has the matches?
We are without matches, according to the Archimedes method, - Lenya blurted out. Mirrors, or what? - the fireman was surprised.
Well yes!
Not true! It has long been proven to be a legend. Archimedes could not set fire to the Roman fleet with mirrors.
But we did it, - Lyonya did not calm down, - which means that Archimedes could.
There was silence. All silently waited for the Chief Fireman to say. He pondered something for a long time and finally said: The investigation is postponed until morning - something needs to be checked.
The next morning Tanya, Irishka and Lenya walked along the river bank. Suddenly they were looking, and on the shore sits the Chief Fireman with a fishing rod and dozes. There is a huge plate next to him.
Why do you need this plate? - asked Lenya.
The firefighter shuddered, woke up, saw Lenya, Irishka and Tanya and said:
Ah ... it's you ... And you look what's inside this plate. Leon looked inside the plate and saw many mirrors. The chief fireman got up, picked up the plate, turned it with mirrors to the sun and said:
Look, the sunlight hits the mirrors, and they direct all the light to one place. Now if you put in this place ...
Log! - Lyonya could not resist.
The chief fireman looked menacingly at Lenya and continued: If you put a frying pan in this place and pour a few eggs on it, then in fifteen minutes we will have scrambled eggs ready.
With these words, the Chief Firefighter put the frying pan on a support made of thick wire, adjusted his mirrored plate so that all the mirror bunnies fell to the bottom of the frying pan, and greased the pan with oil. Was really
it was strange to see how the oil in the frying pan, under which there was no fire or electricity, immediately hissed. The chief fireman broke some of the eggs and poured them into a hot skillet. In two minutes, and not in fifteen, as the Chief Firefighter had promised, everyone - Lenya, Irishka, Tanya, and the firefighter himself - were burning themselves, eating fried eggs, which they fried in the sun.
The experience with burning a log, described at the beginning of the story, is almost impossible to repeat, since this will require at least fifty children, and it is extremely difficult to send fifty bunnies to the same place and keep track of them.
You can do the experiment with several guys by directing the "bunnies" to one of them on the palm of your hand. The child will immediately feel that the palm has become much warmer from the sun bunnies.
Mirror reflectors, assembled from small flat mirrors on a concave surface, or simply large-diameter concave mirrors, are used as solar kitchens in countries with a large number of sunny days. Such mirrors can also be used in open space for welding metals.
A solar kitchen can be made, although it will take some effort and ingenuity. This kind of kitchen works very well. In any case, in 1 - 2 minutes, the eggs will not only be fried, but also have time to burn. You just need to keep in mind that the kitchen works faster if the pan or saucepan is black, because black surfaces absorb heat much better than white ones.
If you fail to build such a kitchen (and this is not surprising, since I already said that such a construction is not easy), you can simplify the experiments by burning the drawings with small concave (magnifying) mirrors or magnifying lenses. You can do this: first, lightly draw a drawing with a pencil on a board or plywood, and then burn it out properly using a mirror or a magnifying lens. The result is a drawing drawn by the sun.
THE PRIMARY CAMERA
King, prince, shoemaker, tailor, who will you be?
- thought Irishka, and the children stood in a circle and waited for someone to drive.
- The king, - said Vanya.
On the golden porch sat the Tsar, Tsarevich,
King...
- Irishka counted, and everyone rushed to hide.
Vera began to drive.
Gosha hid behind the old sleigh, Vanya climbed into the attic of the shed, and little Alenka entered the tall grass, and she was not immediately visible. Lyonya has long looked after a large plywood box that has recently appeared in the yard. Several people could hide in this box at once, but for some reason no one noticed him, and everyone hid in old, long-known places. Therefore, everyone was soon found, and only Leon was still sitting in his dark box and did not see anything.
- Lyonya, get out, we are no longer playing! - Irishka shouted, but Lyonya thought he was being deceived, and continued to sit in complete darkness. Finally he got tired of sitting
idle, and he decided to poke a hole in the wall of the box with a nail. The plywood from which the box was made turned out to be fragile, and soon the little hole was ready.
Lenya looked out into the street
and closed his eyes, the sun was shining so brightly. When his eyes got used to it a little, he saw that they had really found everyone, but the children were playing or had already left, Lyonya did not know. By chance he glanced at the opposite side of the box and froze in surprise. Children ran, walked and sat upside down right on the plywood wall. Lyonya looked at this, looked and how he would shout: A-ah! I have invented a new magic machine!
Only then the children guessed where Lyonya was hiding. They rushed to the box, quickly climbed into it and saw that on the plywood wall of the box there was a house, two sheds upside down, the sky was below, and the earth, overgrown with tall grass, was above. The children on the wall, of course, were not visible, because they were all sitting in the box and screaming with delight.
But the trouble is - no one understood why this strange machine works. Then Tanya appeared. After thinking a little, she said:
You need a lot of flashlights. Carry everyone who has them.
There was no need to ask the children for the second time. A few minutes later, twelve lanterns were lying on the grass near a tree. Tanya took one flashlight and attached it with a piece of plasticine to a tree trunk. Then she turned on the flashlight.
Look, - said Tanya, - the light from the flashlight goes in all directions and hits the hole in the wall of the box. Light passes through the hole, and a bright speck appears on the opposite wall of the box.
Well, - Lyonya did not believe, ran to the box and climbed into it. All the children rushed after him. Yes, indeed, on the wall of the box
a light speck appeared. Lyonya put up his palm, and the speck moved to his palm. The children approached Tanya again.
And why is there a speck at the bottom on the wall, because the flashlight is at the top? - Mashenka asked.
Look closely at the drawing, ”Tanya said and drew a picture with a flashlight and a box, only the box did not have one wall to better see what was going on inside.
The light from the flashlight flies straight like an arrow and therefore, having passed through the hole, it meets the wall below. Tanya waited for everyone to understand her, and attached a second flashlight to the tree trunk. Only this flashlight she attached below, at the very ground.
Where do you get the speck from this flashlight? - Tanya asked, and everyone thought, and then immediately shouted: Up!
Let's check, - said Tanya, lit a flashlight, and the children again rushed to the box. They saw two bright spots in the box. Tanya began to quickly cover and open the lower flashlight with her hand, and the children saw that the upper speck was blinking.
After that, several lanterns were attached to the tree trunk, and a strip of light specks appeared on the side of the box. We made a sharp tip for this strip of flashlights - an arrow turned out. The arrow from the flashlights looks up, and when the light from this arrow passes through the hole in the box, the arrow from the light spots looks down.
- Lanterns shine, but houses, trees and people do not shine, but they still work on the wall, - said Irishka.
Everyone looked at Tanya. Indeed, the truth is, trees and houses do not shine.
- All objects shine, - said Tanya, - some are bright, others are weak. The sun, bulbs and candles shine with their own light, and houses, trees and people - with reflected light. Look around: sunlight is falling on the leaves of the trees. Leaves reflect a lot of sunlight, so they are bright, and tree trunks reflect little, and therefore they are dark. So it turns out that faces, hands, shoes, dresses also glow.
- Not true, - said Lyonya.
- Do not believe me, get into the box.
Lyonya climbed into the box and closed the lid behind him.
- See the sunbeam from the hole? - asked Tanya.
- I see.
- Put up your finger.
Lyonya put his finger under the beam, in the darkness the finger became bright as a light bulb, and the whole box was flooded with pink light.
- Has it become lighter? - asked Tanya.
- Yes!
- Now, substitute a piece of paper. Leon framed a piece of paper. The paper was bluish in color, and this filled the entire box with a blue light.
- Even lighter! - Lyonya shouted.
- Now, substitute the candy foil.
- I do not have it!
- On, - Irishka opened the lid of the box and gave Lena a piece of foil.
- As bright as outside! - Lyonya shouted.
- So, fingers and pieces of paper shine? - asked Tanya.
- They are shining, - Lenya smiled.
Now he understands that when the light from objects enters the box through the hole, then from light objects on the wall light specks are obtained, and from dark objects - dark ones.
These light and dark spots are added together, and an image of objects is obtained.
The next day, the children took a plywood box from under the parcel, punched a hole in the wall with a nail, and removed the top cover so that they could see what was going on in the box. And to prevent extraneous light from falling into the box from above, they covered their heads with a black opaque blanket. Light from objects enters through a hole into the box, and an image of all these objects is obtained on the opposite wall of the box. The children attached a piece of paper to this wall so that the images of the objects were on this piece of paper. The children began to trace the images with a pencil, and soon the whole picture turned out on paper: a yard, a high birch, a shed, and a calf nibbling grass near the shed.
Tanya said that in the old days, when people still did not know how to make photographic film and photographic paper and when there were no modern cameras yet, they used boxes like this with a hole and drew with a pencil on paper. Box is not a scientific word, and people gave the name to this primitive camera "camera obscura".
The children began to paint each other, and by lunchtime they had a whole collection of their own portraits.
By the way, I strongly advise you to make such a camera obscura, and then use it to draw portraits of your friends and family.
Making a camera obscura is not difficult, its structure is clear from the story itself. You just need to keep in mind that the smaller the hole, the sharper the image, but at the same time darker. In practice, it is possible to choose the hole diameter 100-200 times less than the distance from the wall with the hole to the opposite wall, where the image is obtained. You can not only draw images of objects in the camera obscura, as described in the story, but also photograph using such "optics". It is best to take an ordinary camera for this purpose, turn the lens out and replace it with a piece of black paper with a hole pierced by a needle. How to determine the shutter speed in such a case?
First of all, you need to determine the relative aperture (aperture) of such a lens. It is equal to the diameter of the hole divided by the distance from the film to the hole. For example, the hole has a diameter of 0.5 mm, and the distance from it to the film is 50 mm. The relative aperture is 1/100 mm. If you are used to using the expression “aperture”, then the aperture of such a lens is 100. As you can see, our lens cannot be called fast. Then, using an exposure meter (or a table), you can determine the shutter speed for the smallest relative aperture, which is still used in conventional cameras 1/22 (aperture 22). Our aperture is 5 times smaller, which means that the shutter speed should be increased (5X5) 25 times. If for aperture 22 the shutter speed was equal to, say, 1/100 s, then for our lens it will be 25 times longer, that is, 1/4 s. By the way, with the help of such a lens, you can successfully shoot on color film.
QUESTIONS AND TASKS
2. What do we see in the mirror when someone directs a sunbeam into our eyes? Why is the mirror blind in this case?
3. If you turn the mirror so that mom can see in it, who will mom see in the mirror?
4. "Photo" in Greek means "light", and "grapho" means "writing." How to translate the word "photography" from Greek into Russian?
HEAT
IS THE FUR COAT WARMING
Tanya bought ice cream for the children, but forgot that they often have angina. Then she remembered and said:
We come home, the ice cream will melt, then we'll eat it. We came home, put Irishka ice cream on a saucer and waited for it to melt. Lenya also put his
ice cream on a platter and also waiting. I'm already starting to melt! - says Irishka. Now it will melt for me too, - said Leon and ran into the corridor. From there he returned with a fur coat and began to wrap ice cream in it along with a saucer. Lenya has wrapped up ice cream better and is waiting. Irishka has already started to melt. She sits and licks melted ice cream from a saucer. Lenya unwrapped his ice cream, and it was as if nothing had happened. Leon also waited. Irishka is already eating, because almost all her ice cream has melted, and Leni's fur coat doesn't even think of melting. Lyonya ran into the corridor and brought another fur coat. He wrapped his ice cream in two fur coats and waits again. Irishka felt sorry for him, and she says:
Eat mine before you melt.
Come on, don't, - says Lyonya.
A little more time passed, they unrolled both fur coats, and again nothing happened to the ice cream.
It's strange, - says Irishka, - why doesn't ice cream melt in a fur coat?
Tanya at this time stood at the stove. She raised her hand over the hot stove and said:
What should be done so that the hand does not burn?
- Take it away, - Lyonya answered.
- To block her with something from the heat, added Irishka, and she herself took off the board on which the bread is cut and holds it over the stove so that the board is between the stove and Tanya's hand. Heat from the stove does not pass through the board, so Tanya does not burn her hand.
Lyonya looked at this, ran into the hallway and put on a mitten. He holds his hand over the stove, and does not burn it.
“It doesn't burn me either,” says Lyonya.
- So the mitten doesn't warm ...
- ... but retains heat, does not pass it to the hand.
- That's right, - says Tanya, - so what happened to you with ice cream in a fur coat?
Lyonya thought and said:
- When I wrapped the ice cream, the fur coat stopped letting in room heat to him, and this made it cold in the fur coat, so the ice cream did not melt.
- Well, why does a person put on a fur coat in the cold?
- The man left the house, he is hot, and the fur coat is not letting out + heat outside, so the man does not freeze.
“By the way, fur coats come not only from fur, but also from glass,” said Tanya, pouring tea from a thermos.
Hearing these words, Lenya opened his eyes wide in surprise.
- This is a thermos, - as if nothing had happened, Tanya continued, - the walls of the thermos are double, and there is a void between them, and heat passes through the void badly. Fur coats are also made of wood and stone.
- These are the walls near the houses, - Irishka guessed, - they also do not let heat out into the street.
Think and you, what other fur coats are. Where are they used? And answer the question: if a real Snow Maiden puts on her best fur coat, hat, scarf and felt boots and goes to Africa, will she melt there or not?
The experience with ice cream in a fur coat usually works well, but a small layer of ice cream on top still has time to melt rather quickly. In order not to spoil the fur coat, it is better to pre-wrap the ice cream in some clean napkin, and it is necessary to wrap the ice cream in a paper wrapper along with the saucer on which it lies. In order to make sure that ice cream melts more slowly in a fur coat, it is imperative to leave the second portion for comparison, _ not wrapped in a fur coat. The question about the Snow Maiden is not at all as simple as it might seem at first. Often children say that the Snow Maiden is not really there, but she is only in a fairy tale. In a fairy tale, everything can be. This view of things is quite natural for modern children. It is necessary to explain to the child that the experience with the Snow Maiden is imaginary, that real physicists also resort to mental experiments. If the child agrees with you, you can expect at least three responses.
The Snow Maiden will melt from the heat, and the fur coat will help her, as the fur coat is even hotter. This answer is incorrect, since the Snow Maiden is made of snow and it is cold from it in the fur coat.
The Snow Maiden will not melt, like ice cream in a fur coat. One can agree with this answer.
At first, the Snow Maiden will not melt, and then it will melt anyway, since gradually the heat will nevertheless make its way through the fur coat. Such an answer indicates that the child is able to think about the answer deeply enough and is not afraid to state his independent point of view.
BOTTLE THERMOMETER
Lenya fell ill once, he needs to measure his temperature, but he is capricious. Irishka and Tanya were exhausted with him.
- Let's make some funny thermometer, - Tanya said quietly so that Lyonya wouldn't hear.
- Come on! - Irishka was delighted.
They went out to the kitchen, took a small bottle, a rubber stopper and a glass tube.
We ran a hole in the cork with an awl, took a drop of tinted water into the tube and stuck the tube into the cork.
A tube with a tube was inserted into the bottle. The result is a device that anyone can make.
Irishka and Tanya entered the room where Lyonya was lying, put a homemade thermometer on the table.
Let's heat the bottle with our hands, - said Tanya.
Irishka put her hands on the bottle and began to warm it. And almost immediately a drop of colored water crawled up. Before Irishka had time to remove her hands, a drop jumped out of the tube completely.
Why did she jump out? - asked Lenya.
It means that something is pushing her out of the bottle, - said Tanya. - What's in the bottle? - she asked Irishka.
Nothing but air, ”said Irishka.
So she is being pushed out ...
Air, - Lenya put in.
That's right, - Tanya nodded, - why did he start pushing her out?
It is expanding, probably, - said Irishka.
Why did it start to expand?
From the heat, probably, - Leon guessed.
That's right, - Tanya agreed.
Irishka and Tanya took a new drop of tinted water instead of the one that jumped out, but the drop ended up at the very top of the glass tube.
How to lower it down? - asked Tanya.
It is necessary to cool the bottle, - said Irishka, and both began to blow on the bottle. The droplet ran down quickly.
Give me your hand, - said Tanya. Irishka gave her hand, and Tanya put the bottle under her arm. The droplet crept up. Lyonya, Tanya and Irishka watched her closely. So she crawled more slowly, even more slowly, and completely stopped. Tanya rolled out a piece of plasticine and made a ring around the tube in the place where the drop of water stopped.
Since you are not sick, you have a normal temperature, - said Tanya. - We marked this temperature on the straw. What else can we measure? - asked Irishka.
Measure my temperature, - Lenya asked in a plaintive voice.
Tanya and Irishka just needed this. They went up to Lena and put a thermometer from a bottle under his arm. The droplet quickly ran upward and stopped well above the place where the strip marked the normal temperature. The droplet has risen above normal temperature, which means you have a fever, - said Tanya.
If the heat passes, will the drop go down? - asked Lenya.
- Sure. - Give me the medicine! Lenya drank the medicine and waited for the fever to pass. Since it was boring to wait, he
asked Tanya: - Do all objects expand when heated? - Yes, - said Tanya. She took a wire and tied one end of it to a stud that was sticking out of a toy shelf. I attached the other end to the barrier, which I assembled from the designer. Look closely at the drawing You see, the wire is
When a train is traveling on a railroad, the barrier is lowered to stop the cars.
So, the wire is tied to the barrier and thrown over the wheel, and the other end of the wire, as you already know, is tied to
a carnation on the toy shelf.
Lenya looked at this toy and said:
So what?
And that's what!
Tanya took two candles and gave two more to Irishka. They lit candles and brought them to the wire. The heat wire began to expand, or, better to say, lengthen, and the barrier began to fall. The candles were removed, the wire began to shorten and pulled the barrier up. It is very interesting - no one touches the barrier, but it goes down and up itself. While the barrier was being assembled from the constructor, while we were making an experiment with the wire and watching the barrier rise and fall, two or three hours passed. Lyonya remembered the thermometer. Take my temperature again, ”he asked. They put him a thermometer from a bottle. The droplet immediately crept upward, but not so quickly. Soon she stopped, and not just stopped, but exactly against the strip of plasticine, which marked the normal temperature.
Everyone immediately realized that the medicine had worked and Leni's temperature became the same as Irishka's, that is, normal. Very good, - said Tanya. - How would we cure you if we didn't have such a thermometer?
And everyone laughed.
Making a thermometer from a bottle can be difficult due to the lack of a good glass tube. The glass tube can be replaced with an empty plastic (clear) ballpoint refill. You just need to keep in mind that the diameter of the rod is much smaller than the diameter of an ordinary laboratory glass tube, and in order for the thermometer to work well, you need to take a small bottle for the thermometer - 50-100 ml (50-100 g of water).
In order for a drop of tinted water not to jump out at the moment when you insert the cork with a tube into the bottle, you must first insert the cork, and insert the tube with the drop last into the hole drilled in the cork.
The wire lengthening experiment also works well. For greater success, the wire should be taken as long as possible.
(3 - 4 m). A barrier made of a constructor must be firmly and motionlessly fixed on the table with a clamp, some kind of weight, or, if possible, simply nailed. The wire should be heated evenly along its entire length. That is why Tanya and Irishka used four candles, evenly distributed throughout the wire.
Several more experiments can be done to illustrate the expansion of bodies from heating. For example, take a five-kopeck coin, put it on a small board and hammer a carnation into the board along the opposite edges of the coin so that it passes freely between them. After that, the coin must be heated and again try to draw between the nails. If the coin is heated enough, it will not pass between them.
HOW TO TURN THE STEPS TO FIRE
The guys suffered a shipwreck - the boat's oar broke. At that time they were alone on a small island, there was no one to ask for help. And with one oar you cannot reach the shore, because the Ob is a wide river. The children shouted for a long time, but the river seemed to have died out, and they finally realized that it was useless to shout. Everyone was discouraged. Even Tanya did not know what to do. She was sitting on the bank and senselessly twirling a piece of oar in her hands.
- We need to make a fire, - said Lyonya, - maybe they will notice!
- There are no matches. How will you divorce? - said Tanya and threw a piece of oar on the sand.
Suddenly Irishka cries out:
- I know! It is necessary, like primitive people, to rub a stick on a stick, and you get fire.
- Like this? - Leon was surprised.
“When you rub one object against another, both of them heat up from friction,” said Tanya, delighted.
- I don `t understand.
- Give me your hand, - said Irishka. She took Leni's hand in hers, and with the other hand began to rub his palm hard.
- Oh! - Lyonya shouted. It seemed to him that a hot iron was being applied to his hand.
- Do you understand now? - Tanya laughed.
- Now I understand, - said Lyonya, rubbing his palm.
He grabbed two sticks and began to rub them hard against each other, but the sticks got very hot.
- It won't work like that, - said Tanya and began to rotate the wand between her palms, pressing the tip of the wand to the log on which she was sitting.
She rubbed for a long time, so that a hole formed on the log ...
When Tanya decided to take a break, Irishka put her finger to the place where Tanya was rubbing, and said:
- Hot!
- So we will be left without hands, - said Tanya, examining her palms, on which calluses began to appear, - we need to figure out how to twirl a wand. The guys thought about it. Everyone's mood dropped again, as it turned out that getting fire by friction was not easy.
Lenya thought so hard that his face became quite ferocious. He walked back and forth, took the rope that was lying in the boat, turned it over in his hands and looked at the wand lying next to Tanya.
Tanya and Irishka have already begun to guess what Lenya had invented. They took a stick and wrapped the rope around it once. Then they put the stick on the log and pressed it down with a board. Tanya held the board, pressing the stick to the log, and Lenya and Irishka took the ends of the rope in their hands, pulled it up and began to run back and forth. From this, the wand began to spin quickly in one direction or the other. The smoke soon went up. But the flame never appeared.
- You know, our wand needs to make a fur coat, - said Irishka.
- What fur coat? - Leon was surprised.
- From dry leaves, so that the heat is not uselessly dispersed to the sides.
The children quickly brought in a heap of dry leaves and covered the place where the stick rested against the log. They began to run again, the wand twirled again, smoke poured out, and suddenly everyone saw that a dark red tongue of flame flashed between the leaves. Having placed thin dry branches, the children began to observe how the fire ran merrily along the branches.
- Do you know what we invented today? - asked Lenya.
- What?
- We have invented how to transform steps into fire.
- Here we are, genius physicists! - Irishka laughed, and everyone began to dance the dance of the savages and sing a song from the cartoon "Katerok":
Wonder island, wonder island, Living on it is easy and simple, Living on it is easy and simple, Chunga-changa.
Our happiness is constant, Eat coconuts, chew bananas, Eat coconuts, chew bananas, Chunga-changa.
The children had fun, sang and danced until they saw that the sun was setting behind the horizon, and help never came. Apparently, no one paid attention to the fire during the day, and by evening all the boats left for the pier. The fire continued to burn, and the children and Tanya sat sad and gazed into the distance. - Guys, boat! - Irishka cried out. They all jumped up.
First, they heard a distant chirping, and then at dusk they saw a black dot that was moving towards the island.
- Hooray!!! - the children shouted and started waving their hands. And after another five minutes the motorboat was racing towards the shore. The boatman, Tanya, Irishka and Lyonya were sitting in the boat. Irishka and Lyonya were sleeping. And this is not surprising, they experienced a lot during the day and were very tired.
Getting fire by friction is a great art. This requires special types of wood, which may not be at hand. Another thing is much more important for us - to show the transition of mechanical energy (steps) into heat.
The transition of mechanical energy to thermal energy can be observed in many cases. For example, when sawing wood (or metal) with a hacksaw, both the hacksaw and the wood heat up. If you rub your finger on the table with force, then very soon the finger will become hot. Bodies also heat up from impact. If you knock on a piece of metal for a long time with a hammer, both the metal and the hammer heat up. If two stones hit each other in the dark, sparks can be seen. These sparks are small shards of stone, heated red-hot. Modern matches also ignite from friction, only it is easier for us than for primitive people, since the tip of a match is covered with a substance that ignites even from slight friction. Let us return, however, to the production of fire by friction. It doesn’t matter if the experience is not completely successful. You will almost certainly be able to get thick smoke from the stick that rubs against the board. This will be good evidence that friction causes bodies to heat up.
QUESTIONS AND TASKS
1. In the old days in the village, a pot of ready-made hot porridge was wrapped in a fur coat. Why did you do it?
2. There is no air on the moon. When it's daytime on the moon, there is 120 ° heat, when it's night on the moon and the sun hides behind the horizon, there comes 180 ° frost. Why is there no such frost and such heat on Earth? After all, the Sun is no further from the Earth and no closer than from the Moon.
3. In some hot countries people wear wadded robes and fur hats in summer. Why do they do it?
4. In the North, people sometimes build houses out of snow. Why is it warmer in a snow house than outside?
5. When are the wires on the poles tighter - in winter or summer?
6. Why do you think there is a gap between the rails on the railway line at the joints of the rails?
7 Look closely at the room thermometer.
What expands and contracts in this thermometer?
8. Why does the saw get hot when sawing wood or iron?
9. In your opinion, is it possible to make fire by friction if you have a match and a box?
10. Why do sparks bounce off the stone at the lighter when the wheel strikes the stone?
LIQUIDS, GASES AND SOLIDS
WHY A BALLOON TAKES OFF
In the summer, Lyonya went to Kamchatka to visit his father and mother, and Tanya and Irishka went on a tourist trip to Altai.
Once Irishka and Tanya were collecting stones for a collection. They went far from the camp. Suddenly Irishka stumbled and twisted her leg - she could not go further. Tanya carries it on herself. Here is Irishka and says:
Throw me here! If you get to the camp, you will come back with the guys for me.
Don't talk nonsense, Irina! - Tanya answers. - Let's better rest and think about what to do next.
They stopped by a mountain stream, made a fire, and were resting. And all around there was silence, the mountains frowned, looking at Irishka and Tanya ...
Eh, there would be a radio station! - says Irishka.
Or a carrier pigeon at least, - Tanya answers.
Or a red rocket.
Tanya looks at the smoke that spreads along the coast, and says:
The wind is blowing towards the camp ... What if we launch a balloon and tie a note to it!
Irishka shook her head and sighed:
Where to get the ball?
We will glue the ball out of tissue paper, - Tanya answered and took out glue and a pack of tissue paper from her backpack, which they took with them to wrap beautiful stones for their collection.
But we need a gas lighter than air, - Irishka did not calm down, - without this the ball will not rise up?
Usually balloons are inflated with hydrogen or helium, these two gases are lighter than air, so they pull the balloon up. But we have another light gas - hot air. - Why do you think the smoke rises up?
Irishka recalled the experience with a thermometer from a bottle and said: First, all objects expand when heated ... And air, probably, too.
How can you prove it?
Irishka rummaged in her backpack and took out a small iron pipe. She dipped one end of the tube in water so that a water film turned out on it, and closed the other end with her finger. After that, she took a burning twig from the fire and began to heat the pipe. Soon the film at the end of the tube inflated with a bubble and burst. Irishka says to Tanya:
- From heating, the air began to expand and leave the tube.
- So, the air expands from heating, - says Tanya, - it becomes less in the tube, and it becomes ...
- Easier, - Irishka guessed.
- Well, now let's get down to business! - said Tanya and began to spread a sheet of tissue paper on the grass.
Tanya and Irishka cut out twelve strips, similar to palm leaves, and began to glue them together. Work is moving slowly, Irishka says:
- We'll sit there for half a day ... or we'll do it later, only there were no holes neatly.
Tanya put it to dry, and Irishka wrote a note: “I turned my foot in the Valley of Mountain Spirits. We are waiting for help! Irina".
Tanya and Irishka tied a note to the ball and raised it over the fire. The balloon began to quickly fill with hot air, and Irishka felt that it was beginning to burst upward. This hot air, which is lighter than cold air, lifts the ball.
Tanya and Irishka released the ball at once, and it began to rise rapidly upward.
“It pops up like an air bubble in water,” Irishka exclaimed.
- By the way, - said Tanya, - ballooning is called aeronautics.
If a child wants to build a balloon, it is imperative to help him do it.
The ball is made of tissue (model aircraft) paper.
The figure shows a pattern. If the sheet of paper is shorter than the one you need, you can glue the sheets together. After all the parts of the ball have been cut out (12 of them are needed), you can begin to glue them together. It is best to stick together in pairs. There are 6 pairs.
They need to be glued together so that you get 3 ball slices. The greatest difficulties will arise when making the last seams. We advise you to glue a small section of the seam (10 - 15 cm). It is much more convenient and faster. It is best to glue paper with ordinary silicate (stationery) glue. At the top of the ball, you need to glue the hole formed with a small round patch. In general, one should try to keep the number of patches as small as possible, since each of them makes the ball noticeably heavier.
To prevent the smoke hole from getting shaggy, you need to glue it around with a strip of paper 10-15 cm wide. At the same time, this strip will serve to keep the ball stable in the air.
To launch the balloon, you need to choose a calm and preferably cool day. First of all, you need to make a fire and install a bucket with a knocked out bottom or some similar object above it, which will act as a pipe that collects smoke into a single stream. Without such a device, smoke and flames will rush from side to side and not only make it difficult to fill the ball with smoke, but can set the ball on fire.
WHY THE WIND IS BLOWING
The camp duty officer, Seryozha, was lying near the tent and looking into the sky for nothing to do. All the tourists dispersed along the routes, and in the camp, except for Seryozha and two more on duty, there was no one. Suddenly Seryozha noticed a white dot in the sky, which slowly floated out from behind the mountainside. Looking closely, Seryozha saw that it was a balloon heading straight towards the camp. A piece of paper was hanging under the ball, and Seryozha realized that it was a note. But how do you read it? The ball had already begun to move away from the camp when Seryozha grabbed binoculars and began to read. With difficulty he made out: “I twisted my leg in the Valley of Mountain Spirits. We are waiting for help! Irina".
- Guys! Irishka and Tanya were found! - Shouted Seryozha and ran to the kitchen, where there were the rest of the attendants.
And Tanya and Irishka all sat in the same place and were silent. The fire had burned out long ago. The mood was bad.
- Look how the air flows over the arable land, - said Tanya and pointed to the plowed slope of the mountain. And in fact, one could see how the air heated by the sun rises and distant objects tremble and dance from this.
- This hot air, like smoke from a fire, rises up. Irishka was silent. Suddenly she asked:
And if all the air rises, you get an airless space? Tanya smiled, and Irishka slapped herself on the forehead and laughed. If all the air rose, we would suffocate. Simply, when the heated air rises, instead of it, cold air flies in from all sides.
Correctly?
- Yes. Flies and tilts tree branches, flutters flags, drives dust and raises waves on the water.
- Look, - Tanya continued, - the upper clouds go in one direction, and the lower ones - in the other.
- Where is the wind blowing? - Irishka was confused.
- Over the arable land, the sun has heated the air strongly, - said Tanya, - and it rises up, the air is colder over the mountains, and therefore it goes down. Then this cold air heats up below and rises again, and the cooled air from the mountains falls down again. Near the mountains it becomes a lot, and it flies to the arable land.
- It's on the ground, and above? - asked Irishka.
- And above the air flies in the other direction, to the mountains. We sit on the ground and see how the wind drives the upper clouds in one direction, and the lower ones in the other. Beautiful, is not it?
- Highly! - answered Irishka. Her mood is a little better ...
... The stars were shining. It was quiet. Then footsteps of several people were heard walking along the path. It was Seryozha and his friends. Tanya was walking with them. Only Irishka was not visible in the darkness. But if you look more closely, you could see that on the back of one of the guys was not a backpack, but Irishka. She did not see the stars, did not hear the steps - she was fast asleep.
Explaining to the children why the wind blows can be an experience familiar from the elementary school natural history course. If, in cold weather, you open the door to the street and hold a lit candle at the bottom and top of the gap formed, you can observe that the flame of the lower candle is directed towards the interior of the apartment, and the flame of the upper one is directed outward. This happens because warm air in the apartment rises and comes out through the gap at the top, and cold air is heavier, and it enters the room from below. After a while, the cold air heats up in the room, rises up and begins to go outside through the top of the gap, and cold air will come in its place again and again. This is how wind arises in nature. Of course, the reality is much more complicated. A lot of air currents operate simultaneously on Earth, which interact with each other. The picture of air currents becomes even more complicated due to the rotation of the Earth around its axis.
LIQUID STONES
Once a parcel arrived from Kamchatka. That was just joy! Indeed, the package was from dad and mom! They opened the package, took out a note and began to read:
“Our dear Tanya, Irishka and Lenechka! We are very glad that you are not wasting your time, studying physics. We are sending you an interesting film that was shot here for you, but first, guess the riddle, which is wrapped in paper. Kisses, mom and dad. "
Tanya took the package and says:
- What a difficult riddle!
When the package was unfolded, everyone saw a stone from which a rusty, charred knife was sticking out.
- Who stuck it in the stone? - asked Lenya, wide-eyed.
“It doesn't matter who, it’s important how,” Irishka clarified. -
You can't cut a stone with a knife!
- Apparently, this is the mystery of dad and mom, - said Tanya.
Several days passed, but the riddle was never answered.
Once their neighbor, Uncle Vasya, came to visit our friends. He turned the stone in his hands, shook his head and said: We'll have to help you. Get ready early tomorrow morning - come with me to the factory.
There was such a noise at the factory that you had to shout to hear each other. The children did not know where to look, it was so interesting around. Suddenly a red fire will blaze! The whole workshop was lit up with light, and the children sat down in surprise. A shining fiery stream flowed straight out of the brick wall. What is it? - Lyonya shouted.
Melting furnace, - Uncle Vasya answered him.
No, that it flows bright and red?
Tin!
Tin?
Metal is so!
Metal, but flows like water!
That's just it, - shouted uncle Vasya in Lena and Irishka's ears, - red-hot. Here you have a temperature of 36 °, and here - 1000 °. Otherwise it is impossible, because the tin will become solid again. Look!
Uncle Vasya scooped up some tin with an iron ladle on a long wooden handle and poured it on the stone floor. The puddle soon faded and turned into a sheet of white metal. Lyonya wanted to grab him, but Uncle Vasya stopped him in time:
Hot!
Finally the tin cooled down, and Uncle Vasya allowed to take it. At home Lenya said:
It turns out that the stone was also hot and melted at first? It turns out so, - said Tanya. - Let's watch the film, then we will finally understand everything.
Tanya turned on the projector, and a beautiful and scary picture appeared on the screen. A plume of flame and black smoke rose from the top of the high mountain. When the children looked closely, they saw hot stones flying out of the mountain. They rose up with a crash and slowly fell down. Falling on the side of the mountain, they were flattened with red cakes and slowly extinguished.
At the top of the mountain, the children saw a huge hole. Tanya said that this pit is called a crater, and that the crater at the bottom turns into a wide and very deep well that goes
deep into the depths, where the earth is so hot that all the stones are molten and therefore liquid. This well is called a vent. The mouthpiece, like a huge cannon, fired hot stones. And Tanya said that these liquid stones are called volcanic bombs.
Suddenly the children saw a river of fire flowing from one edge of the crater. When we looked closely, we realized that it was molten stones flowing. They were liquid, like sour cream, red, like a ripe watermelon, boiling and bubbling like semolina on the stove, and since the streams of air trembled above them, like over a fire, the children realized that these stones were very hot. Volcanic bombs were again falling from above on the screen. Suddenly, a man approached one bomb and threw a penknife at it with force. The knife stuck in and blazed like wood. When a man in a special silver suit with a face covered with the same mask stepped aside, the children jumped off their seats and shouted:
- Dad! Dad!
Yes, it was their dad, although his face could not be seen because of the mask. The children recognized him by his walk.
- So this stone is a volcanic bomb? - Lenya asked when the film ended.
- Yes, - said Tanya.
- And it was runny from the heat?
- Yes.
- And he was underground before ?!
- Yes.
- This is what an extraordinary stone we have! - said Irishka.
The excursion to the plant described in the story is an interesting business, but not always possible. You can limit yourself to experiments with melting sugar and paraffin and freezing water, which will be discussed in the next story.
Draw the child's attention to the fact that the state of aggregation of a substance depends on the conditions in which this substance is located. If, under normal conditions, metals are solids, then at high temperatures they pass into a liquid state, and at even higher temperatures - into a gaseous state.
It is especially easy to trace the change in the aggregate state of water (solid - ice, liquid - water, gaseous - steam).
SOLID WATER
Lyonya attached a piece of tin to the wall that looked like a blot and said:
- Eh, we would have such a stove, like in a factory, that would have made toys!
Irishka thought about it and answered:
- You know, toys can be made not only from iron, but also from ... sugar.
- From sugar? - Lyonya was dumbfounded.
She poured into a teaspoon (...)
- Carry yours tin soldiers, - said Irishka and began to knead the clay. When Lyonya brought the soldiers, Irishka took one of them and pressed it into a clay cake. In the cake, a soldier-shaped hole turned out.
- What would we pour here? - asked Irishka.
- Let's melt the paraffin!
greased it with butter and poured liquid sugar from the first spoon into it. In order not to burn her hands, Irishka put on 5 woolen mittens. : ap, poured into a spoon, began to cool down, Threat he cooled down faster, chuck into cold water.
The sugar began to melt and fill the spoon like water.
Irishka took another spoon
- Come on!
The children put an iron mug on the tile with a candle stub in it. Soon the candle melted, and liquid paraffin gathered at the bottom of the mug. Irishka again, so as not to burn her hand, put on a mitten and took off the mug from the tile. Holding the mug in her outstretched hand so as not to splash the paraffin on her legs, she went to the table and began to carefully pour the paraffin into the mold. The paraffin took a long time to cool. Above it was already cold, and below it was still melted. Twenty or half an hour later, the paraffin froze, and the children carefully took the soldier out of the clay.
- Listen, - said Lyonya, - probably at the tin soldiers factory they do the same, but not from paraffin, but from tin!
- Probably, - Irishka thought and agreed. Suddenly she said: - And you can still out of the water!
Lenya stared at her and for a long time could not figure out how to make toys out of water, because it is liquid. But suddenly he ran to his room and returned with the molds for sand. After filling the molds with water, he put them in the refrigerator. Three hours passed. The children took the ice out of the molds and were surprised at what beautiful toys they made. Then they made different molds from plasticine, and in them they received ice planes, boats and even a beautiful badge.
When Tanya came home, the children rushed out into the corridor, and Irishka said:
- Close eyes!
Tanya obediently closed it, while Irishka pinned an ice badge to her sweater. Tanya opened her eyes, looked at the unusual badge in surprise and asked:
- What is this badge made of?
The children were silent.
- Out of ice! - Tanya exclaimed when she realized what was the matter. Irishka shook her head and said:
- Out of hard water!
It is very easy to make ice toys, you just need to be patient, as the water in the refrigerator does not freeze instantly. To pin the ice badge (at least for a few minutes), you need to fill the mold with water and put a sewing pin in it so that the sharp tip sticks out of the water.
WHY IT'S RAINING
There was a kettle on the stove and Steam was forced out of the kettle's spout, and this made the window glass fog up.
Irishka was bored, and she drew a muzzle on the glass with her finger.
Suddenly the muzzle burst into tears!
Well, if the steam cools down, it becomes water?
Indeed, Irishka wiped her face off the glass, and her hand immediately became wet ...
- You know, - said Tanya, - that the water evaporates: the puddles dry up, the wet ground after the rain becomes dry again. There is always water vapor in the air, only we do not notice it, because it is invisible. The steam rises up, cools and becomes visible - clouds are obtained. They are made up of tiny water droplets. These droplets are so small and light that they do not fall down, but fly like fluffs. If such a cloud cools harder, the droplets will gather together, become large, heavy and fall to the ground - it is raining. Now think, Irishka, where does the water come from in streams, rivers and seas. Maybe the water will gradually evaporate from the rivers and they dry up? you, too, think about Tanya's questions and answer them.
Pay the child's attention to the fact that water in nature evaporates all the time (puddles and wet linen dry out, barely noticeable steam rises above the river on a hot day, etc.).
Consider steam condensation. To do this, you can do a simple experiment: cover a pot of boiling water with a cold lid. If you lift the lid after a few minutes, water will drip from it.
Invite your child to explain why this is happening.
WHY IS THE SNOW
Tanya and Irishka were skiing in the forest. Snow falls in flakes. There is such beauty around - you can't take your eyes off!
- Irishka, do not lag behind! - Tanya shouts, and Irishka stands as if enchanted, stretched out her hand in a mitten and looks at her. Tanya came back, went up to her and also stopped.
They stand together and examine the snowflakes on a red mitten. Handsomely!
Look, each snowflake is made of tiny ice crystals, - says Tanya. And Irishka herself sees it - she cannot take her eyes off.
The next day was frosty. Tanya and Irishka walked along an alley covered with snow. The sun was shining, the snow was beautifully shining.
I wonder where the clouds come from in winter? - asked Irishka. - After all, water does not evaporate in winter!
Water always evaporates - both in winter and in summer. Only in winter does it evaporate more slowly.
Irishka got used to the fact that Tanya never cheats, but she could not believe that water evaporates in frost.
Look, the linen dries in the cold, - said Tanya.
They went into the courtyard, where the clothes were hung, and Irishka touched it with her hand.
It’s frozen! See, a crust of ice!
This means that the ice is evaporating, - answered Tanya, - after all, by the evening the linen will dry out anyway. There will be no ice or water left.
Well, and the snow evaporates, since it is made of small ice crystals?
Evaporates, only slowly. But the land is huge, look how much snow lies. That’s enough for a cloud. In addition, clouds come to us from hot countries. The steam will freeze in the cloud, and snow is obtained.
Tanya took out the key to the apartment and started blowing on it. The key began to become covered with frost. The longer Tanya blew on him, the layer of frost became thicker and thicker, and the frost itself became fluffier.
Tanya ran her mitten over the key, and frost fell down. Only it was already impossible to understand that it was pouring in - frost or snow.
So snow and frost are one and the same?
Yes, snowflakes are steam frozen in the clouds, and frost is steam that has frozen on glass, iron, tree branches and other objects.
When Tanya and Irishka returned home, Irishka asked:
Why do snowflakes have such beautiful shape?
Tanya thought and said:
You see, ice is made of tiny particles that cannot be seen even with a microscope. These particles are shaped like small hexagons.
Tanya took scissors and quickly cut out several hexagons from the paper.
- When these tiny particles start to stick together, they cannot stick together in a circle or a square. So you get six-pointed stars.
Irishka tried to fold some other figure out of paper hexagons, but nothing came of it. Different stars turned out, but never a square or a circle came out.
Irishka admired these stars for a long time, and then said:
- It's strange, these particles are not visible through a microscope, but how did people know about them?
Tanya was silent and answered:
“They figured it out.
Irishka looked at Tanya and saw that she was not joking. So what she said is true.
Consider with a child; snowflakes. Watch how the laundry dries in the cold. Repeat the experiment with freezing steam on metal objects. Ask your child to explain these phenomena.
QUESTIONS AND TASKS
1. Why does the smoke from the chimney rise up in calm weather? Why does the soot from the chimney eventually fall back to Earth?
2. Imagine that you made a ball out of tissue paper, but you were not allowed to light a fire. How else can you fill a balloon with hot air?
3. When the balloon filled with hot air will rise faster - in winter or summer?
4. Why does the air rise above the arable land, highway, beach on a sunny day?
5. When does the wind benefit people? When does it harm?
6. What machines, devices, toys do you know that work with the help of the wind?
7. Why are stones formed during volcanic eruptions liquid?
8. Can we sometimes say that iron is a liquid? How do you think you can get iron steam?
9. What does the steam turn into when it cools?
10. What substance are snowflakes and frost made of? How to prove it?
11. Where do clouds come from in summer? In winter?
SPACE AND MOTION
HOW DO LILIPUTS DO IN CINEMA
Once on television the film "Golden Key" was shown. The guys really liked it. Lenya then pondered something for a long time and suddenly said:
- Did Buratino play a real artist?
- Real, - answered Tanya.
- And Pierrot?
- And Pierrot.
- And Malvina?
- And Malvina.
- So how did three adults fit on an ordinary table?
- Or maybe this table was made so huge that adults seemed small on it? - said Irishka.
“But Dad Carlo was standing next to me, and it was clearly visible that the table was small! - objected Lenya. This time Tanya did not explain anything to the children. But on the next Sunday she took an amateur movie camera and, together with the children and their friend Igor, went into the forest. We came to the lawn. Tanya says:
Want to show the trick?
We want, - the guys answer.
Tanya put the camera on a tripod, Lenya and Irishka - near the device, and Igor sent to the edge of the clearing. Lenya and Irishka look at the camera and see that Igor is standing far away on the edge of the clearing, and Tanya is next to the camera. Igor is small, and Tanya is large. Suddenly Tanya stretched her hand forward, and Igor was in her palm. Children will scream:
Lilliputian! Lilliputian! - and let's clap your hands.
Look at the footage that Lenya and Irishka filmed then. You see, it seems that Igor is in Tanya's palm. But in fact, Igor is standing far from the camera, and Tanya is close, so it seems that Tanya is big, and Igor is so small that he fits in Tanya's palm.
The children took a walk in the forest, and when they returned to their yard, they taught all the children this trick: squint one eye, stretch your palm forward, and you're done - a man is in your palm. Or you can put the house in the palm of your hand, you just need it to be far away.
Well, but what about the table on which Buratino, Malvina and Pierrot stood? Is it big or small? Take a look at this still from the movie The Golden Key. The ladder is made of two halves. One, on which Daddy Carlo is standing, is of normal size, and the half on which Buratino, Piero and Malvina are standing is huge. This big half and the people who stand on it are far away. Since the line along which the stairs are aligned is almost invisible, it seems that this is one staircase on which little people stand.
The experiments described in the story are simple and easy to repeat. They can be especially interesting if you have a movie camera or a photo camera. Most of all, a camera with a mirror device and frosted glass and cinema cameras such as "Lada" or "Kiev-16" are suitable for filming using the method of perspective alignment described in the story. These cameras are parallax (offset). When removing with a device that has not eliminated parallax, you must constantly take it into account, as recommended in the instructions. The shots where the toys are combined with people can be very interesting. Instead of toys, you can use models of planes, palaces, castles made of cardboard.
Performing work on combined filming, they often shoot two interlocutors, one of whom is sitting at the table, and the second is looking out of a glass, sits on a samovar, walks around the ink device. You can think of a huge number of such frames. Participation in their shooting and viewing will bring great pleasure to children.
The following experience will be very instructive. If you hold a one-kopeck coin in your outstretched hand, you can “shield” the Sun or the Moon with it. Invite the children to explain why the Moon and the Sun look much less than a penny to an earthly observer.
Tell the children why a very beautiful rare natural phenomenon occurs - a solar eclipse.
Orbiting the Earth, the Moon is sometimes located exactly between the Earth and the Sun. Since the distance from the Earth to the Sun is much greater than to the Moon, it covers the Sun, despite the fact that it is many times larger than the Moon.
HOW TO LIVE A SOLDIER
Once Lenya drew a soldier. He turned out to be a handsome soldier. Lyonya looked at him, looked and said:
- I wish I could revive him so that he could march!
- You can make him march, but for this you need to draw a lot of soldiers. Stand, Irishka, against the wall and show us how the soldiers are marching.
Irishka went to the wall and took the pose of a marching soldier. Lyonya quickly drew it.
Move your leg forward a little, - Tanya ordered. Irishka followed her command, and Lyonya made the drawing again.
Look what Lenya drew after Irishka moved her leg eight times.
Very good, - said Tanya. - Cut out a strip of paper on which soldiers are drawn, and cut narrow gaps between the figures. Now roll the strip into a ring so that the drawings are inside, and glue it.
We put the glued strip on the turntable and turned it on. The disk began to rotate, and with it the ring spun.
So what? - asked Lenya.
And here's what, - Tanya answered, - bend down and look at the drawings through the cracks.
Lyonya bent down and looked. At first he opened his mouth in surprise, then he began to laugh. Everyone laughed - Irishka, because she, like Lyonya, saw a whole detachment of soldiers marching on the inner side of the ring, and Tanya was laughing, looking at Lyonya and Irishka. When they calmed down, Lyonya asked:
- Why did the soldiers start marching?
- Because when the ring is spinning, soldiers flash before their eyes, their legs are drawn each time in a slightly different position. Since the pictures change very quickly, we do not notice the change, and it seems to us that the soldiers' legs are moving.
The children liked this toy so much that they made several more such rings, on which they drew a little man who hammered a nail with a hammer; the girl who jumped over the rope; the boy who was skating ...
This ring is called a stroboscope. Draw soldiers or some other figures, as Irishka and Lenya did, cut the gaps between the pictures and glue the rings from strips of paper. Then you will have some strobe lights too.
After you've done your experiments with a stroboscope, try to explain why the characters of the drawn cartoons move on the screen.
WHO GOES WHERE
Once Tanya and Lenya got on the train and were going to go out of town. They sit and look out the window. Suddenly, outside the window everything shuddered and drove back.
- Go! - Leon was delighted.
- Who? - Tanya smiled.
- We, of course.
Tanya was silent, she continued to look out the window. Suddenly Lyonya saw that the train that was standing outside the window had passed, and other trains, the posts on the platform, the station were in their old place. It turns out that it was not Lenya and Tanya who left, but the train that was standing outside the window.
They stood still. Everything shuddered again, but this time Lyonya noticed that not only the train that stood outside the window, but also the posts and the station, had gone back.
Now we have gone, - said Tanya. - Look, there is a village! How she rushes past us! We stand, and she rushes past. No, we are going, - said Lyonya, - look, the guys are waving their hands to us.
Well, yes, it seems to them that they are standing, and the train is moving, but it seems to us that the train is standing, and the guys are going.
Whether we are driving or standing, depends on where to look from, ”Tanya said when they got off the train and stood on the platform of a small station.
We are now standing motionless on the platform, but if you look at us from the Moon through a super-powerful telescope, you can see that we are moving with our Earth.
The principles of the relativity of motion, first formulated by the great Italian scientist Galileo Galilei, and later on a deeper level by Albert Einstein in his theory of relativity, are complex and inaccessible to kids. But the very fact of the relativity of motion is quite clearly revealed by the examples described in the story. Therefore, children need to be introduced to him.
SUNDIAL
Irishka and Lenya walked in the forest. Tired of walking - they began to sunbathe. Irishka fell asleep. Lyonya lay down, lay down, the shadow of the tree moved towards him, he went into the sun and lay down again. He lay still, the shadow moved again. Lyonya moved again. They sunbathed all day, Lenya ran away from the shadows all day. And the next morning he invented the sundial. I drew a circle in the sand and stuck my wand in the center. The sun moves across the sky, the shadow of the wand moves, and the guys mark every hour with dashes where the shadow intersects with the circle.
The next day, everyone sat by the clock and checked them. Please tell me what time is it? - asked Irishka
They put the number 7, and today they were glad that their clock was running correctly. We sat there and waited. From an open window big houseilluminated by the morning sun, the alarm went off.
- Hurray-ah! - the children shouted, because the shadow of the wand lay on the dash, near which the number 8 was written.
But then, when the shadow from the wand approached the number 10, the unexpected happened. First, the chiming of the Kremlin chimes rang out from the open window, then the orchestra played the Anthem of the Soviet Union, and when it ended, the announcer said: “ Good morning, comrades! Moscow time 6 hours. We are starting our rfepe-dachas. "
Lyonya froze in surprise. After all, the sundial was showing the correct time! Why did they say on the radio:
They waited another hour, the shadow of the wand went to the line where 9 was written, but had not yet touched it. The children were very worried: will the clock show the time correctly this time? And at that moment, when the shadow fell on the line, the receiver spoke in one of the windows: “Novosibirsk time is 9 o'clock, we are transmitting the latest news. The children realized that the sundial was accurate.
"Moscow time 6 o'clock", and their clock shows 10? Irishka was the first to guess what was the matter and explained to Lena. She took a large ball, put a dot on one side with a chalk and wrote the letter N. This is Novosibirsk.
Then she put a second full stop and wrote the letter M.
This is Moscow.
Then she lifted the ball over her head and said:
Where the ball is illuminated by the sun is day, and where the shadow is, night. Now Novosibirsk is lit by the sun, and Moscow is still in the shade, which means that it is night there. Then the Earth will turn, and morning will come in Moscow. Got it?
Does the Earth spin? - Lenya asked Tanya, because he did not know whether Irishka was telling him the truth or not.
Spinning, - answered Tanya.
Why, then, is it not visible that it is spinning, because we are standing still? - Lenya asked again.
And you remember, when you were on the train, it also seemed to you that you were standing, and only the village and the pillars outside the window were going. Only the Sun is not “going” by, but the Sun, - Lyonya guessed. - In the morning it is in the east, in the afternoon - in the south, and in the evening - in the west. Correctly?
That's right, - answered Tanya. - And there is also a reason why we do not notice the rotation of the Earth. The earth rotates very smoothly. It does not shake at all like a car or a train. And she turns very slowly. In order for the Earth to turn only once, you need to wait one day and one night.
The construction of the sundial, which is described in the story, is not difficult. But the trouble is that such a clock will not work correctly for long, already in two weeks, their wrong move will be noticeable. The fact is that the height of the path of the Sun in the sky changes from season to season and above the point of the east or west the Sun is in different times not at the same time. Therefore, if you want to make a sundial that will operate constantly, you need to slightly change its design by placing the wand-arrow obliquely towards the north.
The tilt angle should exactly match the latitude of your city or village. Approximately, but with sufficient accuracy for us, the latitude can be determined by measuring the height of the North Star above the horizon using a protractor and a plumb line. If a watch with an undivided dial is taken out into the street and set so that the hand points exactly to the north, then, following the position of the shadow from it by the hour, you can divide the dial.
QUESTIONS AND TASKS
1. Imagine that in your city there is no real airfield, and you need to shoot an airfield with large planes for a movie. How to do it?
2 Imagine that you have a toy castle and you wanted to shoot your friends for a movie near a real castle?
3. Imagine that you wanted to become a giant, how can this be done in a movie or in a photograph?
4. Pay attention that when you ride the carousel, it seems that you are standing still, and the trees and houses are spinning.
5. Why do we not notice how the globe rotates?
6. Why is the time different in many cities, for example, when it is 1 pm in Moscow, 3 pm in Sverdlovsk, 5 pm in Novosibirsk, and 7 pm in Irkutsk?
INERTIA AND REACTIVE MOTION
LAZY WHEELS
The car has broken down, the wheels need to be replaced. A pair of wheels stood on the rails near the depot. A worker came up, leaned on them, but they didn’t go, he still piled up, but they don’t go again. Somehow the lazy have moved, rolling. It's time to stop, and they go on. The worker keeps them with all his strength, but they do not stop.
The stubborn ones barely got up!
Not only wheels in the world are lazy and stubborn.
Irishka put two balls on the asphalt - one heavy and the other light. She pushed a heavy ball, he bumped into a light one, but didn't even notice it, it rolled on. And then, on the contrary, Irishka pushed a light ball. Jumped light
a ball on a heavy one, but where can he cope with such weight and laziness! He jumped aside himself. This means that heavy objects are "lazier" than light ones.
The children were traveling in the bus, in the back seat. There were few passengers. A ball was lying on the floor of the bus next to the children. Suddenly a red light came on at the intersection. I pressed the driver on the brake - the bus began to stop, and the ball continues rolling, does not want to stop. The bus rolled through the entire bus, stopped only at the driver's cabin. The bus stopped at the crossroads and drove on. And the ball is lazy and doesn't want to go anywhere. The bus went forward and the ball rolled back towards the children. It would be more correct to say that the ball did not roll anywhere. He stayed where he was, and the children drove up to him with the bus.
Items are not to blame for being lazy and stubborn. And in order not to offend them, physicists say “inertia” instead of the words “laziness” and “stubbornness”. All objects have inertia.
Lyonya rode on roller skates on the sidewalk, accelerated, and there was a small hole on the sidewalk. The skates stopped, and Lyonya himself was driving forward by inertia, but not driving, but flying straight, he put his hands forward so that his nose would not hit the asphalt. Lyonya stood up, and there was a bump on his forehead. And all because of inertia!
Probably, you also met with inertia. Remember, you are running and suddenly your legs stumbled for something, stopped, and you fly forward by inertia until you fall to the ground. It happens, and vice versa, the bus stands still, and then starts abruptly. The bus has already started, and the passengers are still sitting motionless, and this makes everyone lean back.
It is necessary to draw the child's attention to the fact that inertia is an integral property of objects, that there are no objects that do not possess inertia.
It is very important that inertia manifests itself not only at the moment when the moving bodies stop, but also at the moment when the resting body begins to move. In general, any change in the speed of a body or the direction of its movement leads to the manifestation of inertia.
HOW LENYA BECAME A FOCUSER
Once Lenya decided to become a magician, and Irishka - his artistic director: she came up with tricks and taught them to Lenya. Here are the tricks they came up with.
1. The children hung a weight on a thin, thin thread, and tied a thick thread to the bottom of the weight. You need to pull the thick thread so that it breaks, and the thin one remains intact. He pulled Lenya by the lower thick thread, and the upper thin one immediately broke off, the weight fell and almost hit Lenya on the leg.
- Wrong, - shouts the artistic director, - you need to jerk sharply so that the weight does not have time to budge, because it is heavy and lazy.
Irishka took a thick thread by the end. P-times! A thick thread broke, but a thin one at least.
- Wow! - said the magician and shook his head,
2. Have the children hung up on a gift? " thin paper co-2Sh lechkah wooden shkyak lath. The rack hangs on paper rings, and the rings hang on metal rulers that Leon is holding in his hands. Irishka swung a thick stick - fuck! The rack is shattered, but the rings are intact. Amazing!
Tanya went into the room, saw this trick and said:
- You can not hang the rail at all, but it will still break. She took another rail and threw it up. I hit the rail with a stick, and the rail shattered into two halves with a crash.
- Why? - Tanya asks.
The children thought. They cannot understand why this happens.
- When the stick hit the rail, - said Tanya, - in the middle of the blow she moved forward, and the ends remained in place by inertia. From this, the rail bent so much that it broke.
3. He put Lenya's hand on the table. A brick was placed in his palm, and a walnut was placed on the brick. Irishka took a hammer and hit the walnut. He cracked, and at least something to his hand! The children ate the kernel of a nut and came up with a new trick. They put a brick on Lena's palm, and a second brick on this brick. Irishka hit the top brick with a hammer, it split into halves, but nothing on her hand! Terrible experience! And Tanya laughs: Why doesn't her hand hurt, you understand?
“Because the brick is heavy and lazy,” said Irishka, “when I hit him sharply, he didn't have time to budge, and nothing happened to my hand.
Finally, Leon came up with a trick.
Friends spent the whole evening doing magic tricks, and then they came up with a song:
Lazy things in the world live
Stubborn things in the world live
This stubbornness is called inertia.
In the first focus, the weight, which may not be at hand, can be replaced with any other heavy object, such as a hammer. The only condition for the successful execution of this trick is a sharp movement of the hand when the thread breaks. In addition, the upper thread on which the weight or hammer hangs, by itself, must withstand the weight of the calmly hanging load and not break under its weight.
4. Put Lenya on the palm of his hand a postcard, and on the postcard - a coin and clicked on the postcard. The card flew off my palm, but the coin that was on the card remained. Here's an interesting trick!
It is best to rehearse it yourself before showing this experience to children. During such a rehearsal, you can easily determine the required thickness of the threads and practice your hand. When the children do this experiment, make sure that they do it with an outstretched hand. This is necessary so that in the event of an unsuccessful experience (if the thread still breaks) the weight does not hit the child on the leg.
For the second experiment, you need to take a pine lath with a thickness of about 5 mm and a stick to break the lath 1 - 2 cm thick. The thickness and width of the paper rings can be any, as without them the lath will break. It is only important that, as in the previous experiment, the rings do not break from the weight of the rack even before you hit it with a stick. Roughly, you can make rings from a 1 cm wide strip cut from a regular sheet of notebook paper. Note that a hard hit is needed for the experiment to succeed.
The brick experiment is dangerous at first glance. In reality, it is no more dangerous than the previous ones. It is only necessary to provide that an accidental small fragment of a brick does not get into the eyes. However, usually the brick is broken without splinters. If you or your child find it difficult to overcome the feeling that it will hurt before hitting, hit lightly, and then, gradually increasing the force of the blow, make sure that not only the walnut, but also the second brick can be broken without causing pain to the hand. By the way, in the old days this experience in circuses was presented quite effectively. A man lay down on the carpet, a heavy anvil was placed on his chest. The second man beat her with a sledgehammer with all his might. Unlike the terrified circus spectators, you are well aware that this experience is completely safe, unless, of course, the “hammer” does not miss the anvil. The last experience is quite simple.
"REACTIVE" CANNING BANK
Lenya and Tanya sunbathed on the seashore. Tanya dozed, and Lyonya looked at the sky. Suddenly Lyonya noticed a high-high jet plane.
- Why does a jet plane fly forward, what pushes it? - asked Lenya.
- Hot gases fly out backward and push the plane forward.
I don `t understand.
Tanya got up, went to the boat, which was standing at the shore, put a heavy stone there. Then I looked around, saw a pile of stones and began to carry them into the boat. Lenya began to help. When there were enough stones, Lyonya and Tanya pushed the boat away from the shore and jumped into it. The boat passed a little by inertia and stopped. Then Tanya got up in the boat, took a stone in her hands and said:
I take a stone, it is heavy and lazy, it has a lot of inertia. I’ll throw him back now, but he doesn’t want to fly right away, and therefore I’ll push off a little from him.
R-times! - Tanya threw a stone into the water behind the stern of the boat. The stone was heavy, and Leon noticed that Tanya swayed forward strongly, and the boat also moved a little. Tanya took
second stone. - Two! - and the stone flew back again, and the boat moved forward a little more. Three! - the boat went pretty fast. - Four five six! - shouted Tanya and with force threw stones back, and meanwhile the boat was moving faster and faster.
I throw stones back, and they push our boat forward, which means that our boat is jet! - Tanya shouted cheerfully.
Wow, overclocked! - said Lenya, who did not think that in this way it was possible to make the boat float, and therefore was a little scared. But then the stones ran out, and the boat continued to move forward by inertia. The water that seethed behind the stern, on the bow and under the bottom, gradually slowed down the boat, it sailed more and more slowly and finally stopped.
When they went ashore, Tanya took a tin can and began to punch holes in the wall near the bottom with a nail. Punch a hole and bend the nail to the side. He will also punch a hole and again bend the nail in the same direction. She punched four holes, tied a thread to the jar and ran into the water. Tanya scooped water into the jar and raised it. The can began to spin. This water, flowing out of the holes, spins the can in the other direction. As well as the stones that Tanya threw back, pushed the boat forward.
Lyonya looked at these experiments and was thinking about something all the time. Then he cut off the dry stalk, cut a tube out of it, tied it to
a tube a balloon. Lenya tied a tube with a ball to a small board. Then he inflated a balloon, put the plank on the water and opened the hole by the pipe. Air through the tube began to forcefully leave the ball. Air flew back and pushed the board forward. It turned out to be a funny boat, jet!
Tanya took a balloon with a tube off the boat, inflated it and let it go up. The air whistled and the balloon flew up rapidly.
Like a rocket! - Lyonya shouted.
And this is a rocket, - said Tanya, - only this rocket is air.
The experiment with a tin can with holes punched near the bottom is simple and can be repeated at home. In this case, the string that holds the jar must be tied to the water tap. After unscrewing the tap, fill the jar with water and it will begin to rotate. You can adjust the flow of water so that the can will rotate indefinitely.
A ship in which a rubber ball and a light tube of a suitable diameter play the role of a jet engine is not difficult to make. You can install such an engine on a light cart instead of a boat.
Now you understand what is pushing the jet forward?
- Now I understand, - said Lenya, - these are hot gases that fly out of the plane.
REACTIVE TOYS
Irishka was not at sea, and she was very upset that she missed such interesting experiments. Suddenly Tanya says:
- Get on the bike.
There were two old tricycles in the hallway. Irishka sat on one, and Tanya - on the other. They sat down each to
a friend's face. Tanya says: - Hold on, I'll push you now. Just raise your legs so that they do not touch the floor, and she herself also raised
legs.
After that, she pushed Irishka's bicycle with force, and Irishka went back.
- And she drove off a little, - Irishka laughed, because Tanya also drove back on her bike.
“Now you push,” Tanya said to Irishka.
Irishka pushed Tanya, and again both drove off.
- It doesn't matter who pushes with the hand, both got the push anyway.
- And now let's see who drives off further, - said Tanya and again with force pushed Irishkin's bicycle.
- It's not fair! - Irishka shouted. - - You pushed me hard!
And in fact, Irishka drove far away, and Tanya - a little.
Push me hard so I go far away.
Again Tanya and Irishka drove up to each other, and Irishka pushed Tanya as hard as she could. But instead of going far for Tanya, Irishka went far.
And why? - Irishka asked calmly.
What?
Why do I always travel far?
You are lighter, and you have less inertia, - said Tanya, - remember the experiment with balls. A light ball bumped into a heavy one, pushed it, flew off to the side, and the heavy one just moved a little. Remember, - said Tanya to Irishka and Lena, - no matter who pushes whom, both get a push. You move further "the one in whom the inertia is less, who is lighter.
Tanya took the spring, squeezed it, tied it with a thread and put it on the cart near the wall. Then she lit a match and held it to the thread. The thread is burnt out, the spring straightened and how the cart will hit!
Itself flew to the opposite end of the room, but the cart pushed too, the cart rolled on the table.
Why did the cart push the spring harder? - asked Lenya.
They pushed each other
the same. Only the spring is light, so it flew away further, - smiled.
Tanya.
The children put a fan on the cart. They turned it on.
The fan is spinning, pushing the air backward, and the air pushing it and the cart forward.
Like a propeller at an airplane, - said Lyonya.
Yes, - agreed Tanya.
Is it true that the propeller is a fan? - Lenya asked again.
Yes, only big and strong ..
Listen, - Irishka shouted, - oh, too reactive! Tanya and Lenya looked at Irishka and burst out laughing. But Irishka, not paying attention to them, walked around the room in circles and said:
I push the earth with my feet back, and she pushes me forward, I push the earth back ...
Hurray! - Lyonya and Tanya shouted, who finally understood what Irishka wanted to say. It turns out that all cars, belly-
people and people, when they move, push something back (for example, earth, water, air), while they themselves move forward.
When the children realized this, they made two jet boats. The first has a hole in the back wall of the pipe, into which a thin tube is inserted. If you pour water into a large pipe, it will flow back from the thin tube and push the steamer forward. At the second boat, an elastic band spins a spool of thread into which several metal feathers from the handle are stuck.
The coil spins and the feathers throw the water back. The feathers push the water back, and the water pushes them along with the boat forward.
In the first experiment with bicycles, it is necessary that one of the participants is significantly heavier than the other. It is important to pay attention to the fact that the result will always be the same, regardless of who pushed the bike with his hand. Of course, it is very important that both bicycles are equally light on the move and that the participants in the experiment do not brake with their feet on the floor. Instead of bicycles, you can take any two identical carts. The experience is very good at the ice rink in winter. In this case, the participants in the experiment face each other and push off with their hands. And in this case, the one who is lighter and, therefore, has less inertia, drives away further.
The toys described in the story can be made using drawings. It's good if children take part in making them.
THE TOY THAT CONQUERED SPACE
The children went to bed. Tanya had already turned off the light and was about to leave, when she suddenly heard a whisper:
- Tanya, and Tanya!
- What? - also asked Tanya in a whisper.
- Tell me something, - Lyonya whispered very plaintively.
- It's late, Lenechka.
- Tanya, well, please, - Irishka whispered in the same piteous way. Tanya thought for a minute, and then said:
- What can I tell you? ..
Without turning on the light, she sat down on Lena's bed.
- Listen. A long time ago, a teacher of physics and mathematics by the name of Tsiolkovsky lived in the city of Kaluga. During the day he taught the children at school, in the evenings he was engaged in scientific experiments. More than anything, he wanted to visit the moon and other planets. But how to get there? Maybe on foot?
- There is no sidewalk there, - Lyonya laughed.
- On a steam train?
- There is no railroad!
- On the ship?
- There is no water!
- By plane?
- Isn't it possible? - asked Lenya.
- What are you! There's an airless space, it's empty! - Irishka exclaimed.
“That's the trouble,” Tanya continued, “that there is nothing in space that could be thrown backward in order to push off and fly forward. And then one day Tsiolkovsky remembered about toys, like the ones that we came up with, and invented a space rocket. Hot gases in such a rocket with force fly down and accelerate the heavy rocket up ...
Many years later. I remember April 12, 1961 very well. Early in the morning we all learned that for the first time in the world a man named Yuri Gagarin had gone on space travel. He was the very first astronaut on Earth.
Since then, many people have flown into space. Spaceships have visited the Moon, Venus, Mars, Jupiter, and all of them were pushed forward by jet engines.
The events described in this story are well known to everyone. Children are very fond of talking about space and space flights, so you will have such conversations more than once, and it’s up to you how and in what direction to direct them. The only purpose of the story is to draw the attention of children to the fact that inertia or "laziness" and "stubbornness" of the bodies helped people to carry out interplanetary flights. I hope that after reading all the stories, children will be able to understand that almost any movement on Earth and in space is reactive, since animals and machines always push something back, and this “something” pushes both animals and humans, and the car forward. An exception to jet propulsion should be considered movement strictly by inertia, when nothing prevents the body from moving and nothing inhibits its movement. Obviously, such movement is impossible anywhere in real space, since the medium slows down the movement of bodies or bends their path. In both cases, the movement becomes reactive, although it is somewhat more difficult to imagine this than the simple forms of reactive propulsion described in the stories.
WHY SHIP SAILS
Children rode a sailboat on the lake with their friend Igor. Here Igor says:
Something I don't understand: why is the wind blowing sideways, and our ship is sailing forward?
And the truth! - said Lenya. - The wind drives the waves in one direction, and the ship sails in the other.
Why does our ship need sails? - asked Tanya.
For beauty, - said Igor.
Nobody laughed, so nobody knew it.
Eh, you sailors, - Tanya smiled. - What needs to be done to make the ship sail forward?
You need to throw something back, for example stones, - Irishka said uncertainly.
Or air, - added Tanya.
And how to throw it back, because it blows to us sideways? - Leon was surprised.
That's why the sails are made, - answered T chya and looked up. - Look, the sails are oblique to the wind, see?
Yes! - the guys answered in unison.
The wind blows into such a sail and bounces back. It itself bounces back, and the ship pushes forward. Clear?
Yes, - the children answered uncertainly, and it was evident that they did not really understand how the wind blowing sideways to the sails bounced back.
Like a sunbeam from an inclined mirror! - Irishka suddenly guessed.
Like a ball from the wall, - added Lyonya, who also understood.
But what if the wind blows from the other side? - Igor did not calm down.
It is necessary to turn the sails, - answered Tanya, - for this, ropes are pulled from each sail, which sailors call sheets. Pull the sheet and the sail will turn in the right direction.
The wind was weak, but the sailboat easily ran forward, since all the sails were set and the winds captured a lot, captured and directed all this wind backward, since they were all turned to the wind in the same way.
Can sails only work on water? - Leon asked suddenly.
No, everywhere, - answered Tanya.
Summer has passed, autumn has come. A cold autumn wind blew. And in one of these
On windy days, a strange car drove into the courtyard of the house where the guys lived. It was a baby carriage with a sail attached to the mast. The result is a dry-YAO / good sailing ship, or, scientifically, a "wind-sail car". The "wind sail" was small, so we decided to put Igor, the youngest of the children, in it. The "wind sail" with Igor on board was rolled out onto an asphalt road, on which no cars drove, they waited until the wind was blowing stronger,
and released.
The wind-inflated sail pulled the carriage forward, and it ran merrily along the road.
Igor shouted with joy.
Of course, not every reader will undertake the construction of a sailboat on which our heroes sailed on the lake, but this is also. not necessary, since it is no less interesting to control a small toy sailboat. A child will be able to control such a ship independently, without the help of adults, and this, perhaps, will give him even greater joy than a trip on a real sailboat .. It is very easy to make a "wind sail car", or, in other words, a land yacht, which is now very popular and in adults.
OLD MILL
Irishka walked from school, met Igor on the street. They sat down on a bench in the park. On the roof of the house opposite, a wooden turntable spun in the wind. Suddenly Igor noticed that the turntable was spinning not in the direction of the wind, but across.
- Why does the turntable spin across? he asked Irishka, who was also looking at the turntable.
- We need to think about it, - said Irishka and took out a sheet of paper from her portfolio. She folded this sheet crosswise, tore off the corners and began to bend them towards the center. Turned out beautiful flower from paper.
- Do you have a carnation? - asked Irishka.
- Yes, - Igor answered and gave her a small carnation.
Irishka pierced this flower with a carnation right in the middle. The result is a paper turntable, which many guys know.
Look, - says Irishka, - the wind hits the blade, and it stands obliquely to the wind, so the wind bounces to the side. He bounces himself in one direction, and pushes the turntable in the other, so it starts spinning.
And you can make another turntable, - said Igor. He took two small pieces of paper, attached them to the ends of a stick, and nailed it to another stick. When he raised his turntable above his head, it spun merrily. With joy Igor rushed along the alley, and the turntable spun more
In the evening, the children rode their bicycles, each bicycle had a spinner attached to the handlebars. When the bicycles rode down the alley, the turntables spun, and this made the bicycles a bit like airplanes.
Once Tanya, Lenya and Irishka were in the field. Suddenly Lyonya stopped rooted to the spot. Everyone looked ahead and immediately understood why Lenya was so surprised. On the horizon, towering on a hill, a windmill flapped its wings. The guys wanted to look at her better, and they hurried to the mill. Coming closer, the guys noticed a small door. They entered it and saw two large wooden wheels with teeth. The logs on which the wheels were fixed spun with a plaintive creak. Below, near a large stone circle, stood
old man.
- Hello, - said the children. - Hello, - the old man answered and smiled, -
what good do you say?
- We walked across the field and saw your mill, decided to take a closer look, - answered Tanya.
“Well, well done,” said the old man, “she has been decorating our places in recent days. You're in luck, you had time to look. One of these days it will be disassembled and taken to an open-air museum, otherwise it will fall apart here unattended.
- And you? - asked Irishka.
- What about me? - the old man shrugged his shoulders. - I grinded flour on it for the last time forty years ago, since then there is no need for it, the electricity is now working. Are you, of course, interested to see how it works? the old man asked.
“Yes,” the children answered.
- The most important thing at the mill is the wings. The wings are such a large spinner that rotates under the influence of the wind. The wings set in motion that large log, which through the window enters from the street into the mill. On this log is a cogwheel. The teeth engage in the pits on the second wheel. The second wheel turns and turns the millstone with the help of the second log.
- What? - Lyonya did not understand.
“The millstone,” repeated the old man, “is a large round stone. The mill has two millstones. One is motionless and the other is spinning. The millstones are ground with grain, which is poured between them, and flour is obtained. Dough is made from this flour. And bread is baked from dough. Now it is clear? the old man asked.
- I see, - said the children, - thanks!
“Please,” the old miller smiled.
In our time, few readers will have a chance to see a windmill or wind turbine. Therefore, it is necessary, apparently, to limit ourselves to the manufacture of turntables. Since the device of the described turntables is not complicated and can be clearly seen in the figures, we will not dwell on this in detail. It is important to draw the child's attention to the fact that the spinner is spinning perpendicular to the direction of the wind, i.e. if the wind, say, blows from north to south, then the spinner is spinning in the east-west plane.
WHY A KNEE TAKES OFF
Tanya, Irishka and Igor walked down the street. They look - there is a kite in the sky, high! high!
I wonder why it takes off? - Igor said. The wind is blowing ... - answered Irishka.
The wind blows on the ground, and the kite flies up! - Igor almost shouted. Irishka took a piece of paper and said:
Look, the serpent is leaning towards the direction of the wind. The wind hits him, bounces himself down, and pushes him up.
When the wind hits the lower side of the kite, a lot of air collects from below, this air pushes the kite up, - added Tanya.
In the evening, Tanya took out a plywood box, poured pebbles into it - small pebbles that the guys brought from the sea.
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QUESTIONS AND TASKS
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