Spring break is approaching, and many parents are wondering: what to do with children? Home experiments in physics - for example, from the book “Experiments of Tom Tit. Amazing Mechanics is a great pastime for younger students. Especially if the result is such a useful thing as an air gun, and the laws of pneumatics become clearer.

Sarbakan - air gun

Air is widely used in various modern technical devices. Vacuum cleaners work with it, car tires are pumped with it, and they are also used in wind guns instead of gunpowder.

The blowgun, or sarbakan, is an ancient hunting weapon that was sometimes used for military purposes. It is a tube 2-2.5 meters long, from which, under the action of air exhaled by the shooter, miniature arrows are ejected. In South America, on the islands of Indonesia and in some other places, the sarbakan is still used for hunting. You can make a miniature of such a blowgun yourself.

What will be required:

• plastic, metal or glass tube;
• needles or sewing pins;
• drawing or painting brushes;
• insulating tape;
• scissors and threads;
• small feathers;
• foam rubber;
• matches.

An experience. The body for the sarbican will be a plastic, metal or glass tube 20-40 centimeters long and with an inner diameter of 10-15 millimeters. A suitable tube can be made from the third leg of a telescopic rod or ski pole. The tube can be rolled up from a sheet of thick paper, wrapped on the outside with electrical tape for strength.

Now one of the ways you need to make arrows.

First way. Take a bunch of hair, for example, from a drawing or paint brush, tie it tightly with a thread from one end. Then insert a needle or pin into the resulting knot. Secure the structure by wrapping it with electrical tape.

The second way. Instead of hair, you can use small feathers, such as those stuffed with pillows. Take a few feathers and wrap their outer ends with electrical tape directly to the needle. Using scissors, cut the edges of the feathers to the diameter of the tube.

The third way. The arrow can be made with a match shaft, and the “feathering” can be made of foam rubber. To do this, stick the end of a match in the center of a foam rubber cube measuring 15-20 millimeters. Then tie the foam rubber to the matchstick by the edge. Using scissors, shape a piece of foam rubber into a cone shape with a diameter equal to the inner diameter of the sarbican tube. Attach a needle or pin to the opposite end of the match with electrical tape.

Put the arrow into the tube with the point forward, put the tube to your closed lips, and opening your lips, blow sharply.

Result. The arrow will fly out of the tube and fly 4-5 meters. If you take a longer tube, then with a little practice and choosing the optimal size and mass of arrows, you can hit the target from a distance of 10-15 meters.

Explanation. The air blown out by you is forced to exit through the narrow channel of the tube. At the same time, the speed of its movement greatly increases. And since there is an arrow in the tube that prevents the free movement of air, it also contracts - energy accumulates in it. Compression and accelerated air movement accelerate the arrow and give it enough kinetic energy to fly some distance. However, due to friction against the air, the energy of the flying arrow is gradually consumed, and it flies.

Pneumatic lift

You've no doubt had to lie on an air mattress. The air it is filled with is compressed and easily supports your weight. Compressed air has a lot of internal energy and exerts pressure on surrounding objects. Any engineer will tell you that air is a wonderful worker. With its help, conveyors, presses, lifting and many other machines work. They are called pneumatic. This word comes from the ancient Greek "pneumotikos" - "inflated with air." You can test the power of compressed air and make the simplest pneumatic lift from simple improvised items.

What will be required:

• thick plastic bag;
• two or three heavy books.

An experience. Place two or three heavy books on the table, for example in the shape of the letter "T", as shown in the figure. Try blowing on them to make them fall or roll over. No matter how hard you try, you're unlikely to succeed. However, the power of your breath is still enough to solve this seemingly difficult task. Pneumatics should be called for help. To do this, the air of breathing must be “caught” and “locked”, that is, made compressed.

Place a bag of dense polyethylene under the books (it must be intact). Press the open end of the bag to your mouth with your hand and start blowing. Take your time, blow slowly, because the air will not go anywhere from the bag. Watch what happens.

Result. The package will gradually inflate, lift the books higher and higher, and finally knock them over.

Explanation. When air is compressed, the number of its particles (molecules) per unit volume increases. Molecules often hit the walls of the volume in which it is compressed (in this case, the package). This means that the pressure from the side of the air on the walls increases, and the more, the more the air is compressed. The pressure is expressed by the force applied to the unit area of ​​the wall. And in this case, the force of air pressure on the walls of the bag becomes greater than the force of gravity acting on the books, and the books rise.

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Comment on the article "Entertaining physics: experiments for children. Pneumatics"

Home experiments for children. Experiments and experiments at home: entertaining physics. Experiments with children at home. Entertaining experiments with children. Popular Science.

Discussion

We had this at school, only without leaving, they invited a scientist, he showed interesting spectacular chemical and physical experiments, even high school students sat with their mouths open. some children were invited to take part in the experiment. And by the way, going to the planetarium is not an option? it's very cool and interesting

Experiments in physics: Physics in experiments and experiments [link-3] Cool experiments and revelations Igor Beletsky [link-10] Experiments for Simple Home experiments: physics and chemistry for children 6-10 years old. Experiments for children: entertaining science at home.

Discussion

Home children's "laboratory" "Young chemist" - very interesting, attached booklet with a detailed description of interesting experiments, chemical elements and reactions, well, the chemical elements themselves with cones and various devices.

a bunch of books with a detailed description of how to do it and explanations of the essence of the phenomena that I remember: "Useful experiments at school and at home", "The Big Book of Experiments" - the best, in my opinion, the best, "set experiments-1", "set experiments-2 "," we set experiments-3 "

Home experiments in physics - for example, from the book "Experiments by Tom Tit. From the sixth grade, my father gave me to read all sorts of books on entertaining physics. And it is interesting in it for both children and adults. So we decided to visit it. Physics experiment for kids: how to prove rotation...

Discussion

Glen Veccione. 100 most interesting independent scientific projects. ASTrel Publishing House. Various experiments, there is also a section "Electricity".

I won’t say for sure for electricity, you have to flip through. Sikoruk "Physics for kids", Galpershtein "Entertaining physics".

Home experiments: physics and chemistry for children 6-10 years old. Experiments for children: entertaining science at home. Chemistry for younger students.

Discussion

School textbooks and school curriculum - sucks! For older students, Glinka's "General Chemistry" is good, but for kids ...
From the age of 9, mine has been reading children's chemical encyclopedias (Avanta, a couple of others, L. Yu. Alikberova "Entertaining Chemistry" and her other books). There is the same Alikberova book of home experiments.
I think that you can tell children about atoms and electrons with more caution than about "where did I come from", because. this matter is much more complex :)) If the mother herself does not really understand how electrons run in atoms, it’s better not to powder the child’s brains at all. But at the level: they mixed, dissolved, a precipitate fell out, bubbles went, etc. - Mom is quite capable.

09/06/2004 02:32:12 PM, flowerpunk

Home experiments: physics and chemistry for children 6-10 years old. Simple but impressive chemistry experiments - show the kids! Experiments for children: entertaining science at home.

Discussion

At the Kolomna Fair, I saw entire portable "laboratories" for home use in both chemistry and physics. However, I haven't bought it myself yet. But there is a tent in which I constantly buy something for the child's creativity. There is the same saleswoman in the tent all the time (in any case, I get the same one). So she advises whatever - everything is interesting. She also spoke very well about these "laboratories". So you can trust. There I also saw some kind of "laboratory" developed by Andrey Bakhmetiev. In my opinion, something in physics too.

We bring to your attention 10 amazing magic tricks, experiments, or science shows that you can do with your own hands at home.
At your child's birthday party, weekend or vacation, make the most of your time and become the center of attention of many eyes! 🙂

An experienced organizer of scientific shows helped us in preparing the post - Professor Nicolas. He explained the principles behind a particular focus.

1 - Lava Lamp

1. Surely many of you have seen a lamp that has a liquid inside that imitates hot lava. Looks magical.

2. Water is poured into sunflower oil and food coloring (red or blue) is added.

3. After that, we add effervescent aspirin to the vessel and observe a striking effect.

4. During the reaction, colored water rises and falls through the oil without mixing with it. And if you turn off the light and turn on the flashlight, the "real magic" will begin.

: “Water and oil have different densities, and also have the property of not mixing, no matter how we shake the bottle. When we add effervescent tablets inside the bottle, they dissolve in water and begin to release carbon dioxide and set the liquid in motion.”

Want to put on a real science show? More experiences can be found in the book.

2 - Experience with soda

5. Surely at home or in a nearby store there are several cans of soda for the holiday. Before you drink them, ask the guys the question: “What happens if you submerge soda cans in water?”
Drown? Will they swim? Depends on the soda.
Invite the children to guess in advance what will happen to a particular jar and conduct an experiment.

6. We take the cans and gently lower them into the water.

7. It turns out that despite the same volume, they have different weights. That is why some banks sink and others do not.

Commentary by Professor Nicolas: “All our cans have the same volume, but the mass of each can is different, which means that the density is different. What is density? This is the value of mass divided by volume. Since the volume of all cans is the same, the density will be higher for one of them, whose mass is greater.
Whether a jar will float in a container or sink depends on the ratio of its density to that of water. If the density of the can is less, then it will be on the surface, otherwise the can will go to the bottom.
But what makes a regular cola can denser (heavier) than a diet drink can?
It's all about the sugar! Unlike ordinary cola, where granulated sugar is used as a sweetener, a special sweetener is added to diet cola, which weighs much less. So how much sugar is in a typical soda can? The difference in mass between regular soda and its dietary counterpart will give us the answer!”

3 - Paper cover

Ask the audience a question: “What happens if you turn a glass of water over?” Of course it will spill! And if you press the paper to the glass and turn it over? The paper will fall and the water will still spill on the floor? Let's check.

10. Carefully cut out the paper.

11. Put on top of the glass.

12. And carefully turn the glass over. The paper has stuck to the glass, as if magnetized, and the water does not pour out. Miracles!

Commentary by Professor Nicolas: “Although this is not so obvious, but in fact we are in the real ocean, only in this ocean there is not water, but air that presses on all objects, including us, we just got used to it to this pressure that we do not notice it at all. When we cover a glass of water with a piece of paper and turn it over, water presses on the sheet on one side, and air on the other side (from the very bottom)! The air pressure turned out to be greater than the pressure of the water in the glass, so the leaf does not fall.

4 - Soap Volcano

How to make a small volcano erupt at home?

14. You will need baking soda, vinegar, some dish detergent and cardboard.

16. Dilute vinegar in water, add washing liquid and tint everything with iodine.

17. We wrap everything with dark cardboard - this will be the “body” of the volcano. A pinch of soda falls into the glass, and the volcano begins to erupt.

Commentary by Professor Nicolas: “As a result of the interaction of vinegar with soda, a real chemical reaction occurs with the release of carbon dioxide. And liquid soap and dye, interacting with carbon dioxide, form a colored soap foam - that's the eruption.

5 - Candle pump

Can a candle change the laws of gravity and lift water up?

19. We put a candle on a saucer and light it.

20. Pour tinted water on a saucer.

21. Cover the candle with a glass. After a while, the water will be drawn into the glass against the laws of gravity.

Commentary by Professor Nicolas: What does the pump do? Changes pressure: increases (then water or air begins to “run away”) or, conversely, decreases (then gas or liquid begins to “arrive”). When we covered the burning candle with a glass, the candle went out, the air inside the glass cooled, and therefore the pressure decreased, so the water from the bowl began to be sucked in.

Games and experiments with water and fire are in the book "Experiments of Professor Nicolas".

6 - Water in the sieve

We continue to study the magical properties of water and surrounding objects. Ask someone present to put on a bandage and pour water through it. As we can see, it passes through the holes in the bandage without any difficulty.
Bet with others that you can make it so that water will not pass through the bandage without any additional tricks.

22. Cut off a piece of bandage.

23. Wrap a bandage around a glass or champagne glass.

24. Turn the glass over - the water does not spill out!

Commentary by Professor Nicolas: “Due to such a property of water as surface tension, water molecules want to be together all the time and it is not so easy to separate them (they are such wonderful girlfriends!). And if the size of the holes is small (as in our case), then the film does not tear even under the weight of water!”

7 - Diving bell

And to secure your honorary title of Water Mage and Master of the Elements, promise that you can deliver paper to the bottom of any ocean (or bath or even a basin) without soaking it.

25. Have those present write their names on a piece of paper.

26. We fold the sheet, put it in a glass so that it rests against its walls and does not slide down. Immerse the leaf in an inverted glass to the bottom of the tank.

27. Paper stays dry - water can't get to it! After you pull out the sheet - let the audience make sure that it is really dry.

Physics surrounds us absolutely everywhere and everywhere: at home, on the street, on the road ... Sometimes parents should draw the attention of their children to some interesting, yet unknown moments. An early acquaintance with this school subject will allow some child to overcome fear, and some to become seriously interested in this science, and perhaps for some it will become fate.

With some simple experiments that you can do at home, we propose to get acquainted today.

PURPOSE OF THE EXPERIMENT: See if the shape of an item affects its durability.
MATERIALS: three sheets of paper, adhesive tape, books (weighing up to half a kilogram), an assistant.

PROCESS:

Fold the pieces of paper into three different shapes: Form A- fold the sheet in three and glue the ends, Form B- fold the sheet in four and glue the ends, Form B- roll the paper into a cylinder shape and glue the ends.

Put all the figures you have made on the table.

Together with an assistant, at the same time and one at a time, put books on them and see when the structures collapse.

Remember how many books each figure can hold.

RESULTS: The cylinder holds the largest number of books.
WHY? Gravity (attraction to the center of the Earth) pulls books down, but paper supports do not let them in. If the earth's gravity is greater than the resistance of the support, the weight of the book will crush it. The open paper cylinder turned out to be the strongest of all the figures, because the weight of the books that lay on it was evenly distributed along its walls.

_________________________

PURPOSE OF THE EXPERIMENT: Charge an object with static electricity.
MATERIALS: scissors, napkin, ruler, comb.

PROCESS:

Measure and cut a strip of paper from the napkin (7cm x 25cm).

Cut long, thin strips of paper, LEAVING the edge intact (according to the drawing).

Comb your hair quickly. Your hair must be clean and dry. Bring the comb close to the paper strips, but do not touch them.

RESULTS: Paper strips stretch to the comb.
WHY?"Static" means motionless. Static electricity is negative particles called electrons gathered together. Matter consists of atoms, where electrons rotate around a positive center - the nucleus. When we comb our hair, the electrons seem to be erased from the hair and fall on the comb "The half of the comb that touched your hair has received! a negative charge. The paper strip is made of atoms. We bring the comb to them, as a result of which the positive part of the atoms is attracted to the comb. This attraction between the positive and negative particles is enough to lift the paper stripes up.

_________________________

PURPOSE OF THE EXPERIMENT: Find the position of the center of gravity.
MATERIALS: plasticine, two metal forks, a toothpick, a tall glass or a jar with a wide mouth.

PROCESS:

Roll the plasticine into a ball with a diameter of about 4 cm.

Insert a fork into the ball.

Insert the second fork into the ball at an angle of 45 degrees with respect to the first fork.

Insert a toothpick into the ball between the forks.

Place the toothpick with the end on the edge of the glass and move towards the center of the glass until balance is reached.

NOTE: If balance cannot be achieved, reduce the angle between them.
RESULTS: At a certain position of the toothpick, the forks are balanced.
WHY? Since the forks are located at an angle to each other, their weight is, as it were, concentrated at a certain point of the stick located between them. This point is called the center of gravity.

_________________________

PURPOSE OF THE EXPERIMENT: Compare the speed of sound in solids and in air.
MATERIALS: a plastic cup, an elastic band in the form of a ring.

PROCESS:

Put the rubber ring on the glass as shown in the picture.

Put the glass upside down to your ear.

Jingle the stretched rubber band like a string.

RESULTS: A loud sound is heard.
WHY? The object sounds when it vibrates. Making vibrations, he strikes the air or another object, if it is nearby. The vibrations begin to spread through the air that fills everything around, their energy affects the ears, and we hear a sound. Oscillations propagate much more slowly through air—a gas—than through solid or liquid bodies. The vibrations of the gum are transmitted to both the air and the body of the glass, but the sound is heard louder when it comes to the ear directly from the walls of the glass.

_________________________

PURPOSE OF THE EXPERIMENT: Find out if temperature affects the jumping ability of a rubber ball.
MATERIALS: tennis ball, meter rail, freezer.

PROCESS:

Stand the rail vertically and, holding it with one hand, place the ball on its upper end with the other hand.

Release the ball and see how high it bounces when it hits the floor. Repeat this three times and estimate the average jump height.

Place the ball in the freezer for half an hour.

Again measure the height of the jump by releasing the ball from the top end of the rail.

RESULTS: After freezing, the ball bounces not so high.
WHY? Rubber is made up of a myriad of molecules in the form of chains. In heat, these chains easily shift and move away from each other, and thanks to this, the rubber becomes elastic. When cooled, these chains become rigid. When the chains are elastic, the ball jumps well. When playing tennis in cold weather, you need to consider that the ball will not be as bouncy.

_________________________

PURPOSE OF THE EXPERIMENT: See how the image appears in the mirror.
MATERIALS: mirror, 4 books, pencil, paper.

PROCESS:

Put the books in a pile and lean a mirror against it.

Place a sheet of paper under the edge of the mirror.

Put your left hand in front of a piece of paper, and put your chin on your hand so that you can look in the mirror, but not see the sheet on which you have to write.

Looking only in the mirror, but not at the paper, write your name on it.

Look what you wrote.

RESULTS: Most, and maybe even all, of the letters turned out to be upside down.
WHY? Because you wrote while looking in the mirror, where they looked normal, but on paper they are upside down. Most letters will turn upside down, and only symmetrical letters (H, O, E, B) will be correctly written. They look the same in the mirror and on paper, although the image in the mirror is upside down.

Entertaining experiences.
Extracurricular activities for middle classes.

Extra-curricular physics event for middle grades "Entertaining experiments"

Event goals:

Develop cognitive interest, interest in physics;
- develop competent monologue speech using physical terms, develop attention, observation, the ability to apply knowledge in a new situation;
- to teach children to benevolent communication.

Teacher: Today we will show you entertaining experiments. Look carefully and try to explain them. The most distinguished in the explanation will receive prizes - good and excellent marks in physics.

(Students in grade 9 show experiments, and students in grades 7-8 explain)

Experience 1 "Without getting your hands wet"

Equipment: plate or saucer, coin, glass, paper, matches.

Conduct: Put a coin on the bottom of a plate or saucer and pour some water. How to get a coin without even getting your fingertips wet?

Solution: Light the paper, put it into the glass for a while. Turn the heated glass upside down and place on a saucer next to the coin.

As the air in the glass is heated, its pressure will increase and some of the air will escape. The remaining air will cool after a while, the pressure will decrease. Under the action of atmospheric pressure, water will enter the glass, freeing the coin.

Experience 2 "Raising a dish of soap"

Equipment: a plate, a piece of laundry soap.

How to do it: Pour water into a bowl and drain immediately. The surface of the plate will be damp. Then a bar of soap, strongly pressing against the plate, turn several times and lift it up. At the same time, the plate will also rise with soap. Why?

Explanation: The rise of the dish of soap is due to the attraction of the molecules of the dish and the soap.

Experience 3 "Magic water"

Equipment: a glass of water, a sheet of thick paper.

Conduct: This experience is called "Magic Water". Fill a glass with water to the brim and cover with a sheet of paper. Let's turn the glass. Why doesn't water pour out of an overturned glass?

Explanation: Water is held by atmospheric pressure, i.e. atmospheric pressure is greater than the pressure produced by water.

Notes: Experience is better with a thick-walled vessel.
When turning the glass, a piece of paper must be held by hand.

Experience 4 "Tearable paper"

Equipment: two tripods with clutches and paws, two paper rings, rail, meter.

Conduct: We hang the paper rings on tripods at the same level. We put a rail on them. With a sharp blow with a meter or a metal rod in the middle of the rail, it breaks, and the rings remain intact. Why?

Explanation: The interaction time is very short. Therefore, the rail does not have time to transfer the received impulse to the paper rings.

Notes: The width of the rings is 3 cm. The rail is 1 meter long, 15-20 cm wide and 0.5 cm thick.

Experience 5 "Heavy Newspaper"

Equipment: rail 50-70 cm long, newspaper, meter.

Conduct: Put a rail on the table, a fully unfolded newspaper on it. If you slowly put pressure on the hanging end of the ruler, then it falls, and the opposite one rises along with the newspaper. If you sharply hit the end of the rail with a meter or hammer, then it breaks, and the opposite end with the newspaper does not even rise. How to explain it?

Explanation: Atmospheric air exerts pressure on the newspaper from above. By slowly pressing the end of the ruler, air penetrates under the newspaper and partially balances the pressure on it. With a sharp blow, due to inertia, air does not have time to instantly penetrate under the newspaper. The air pressure on the newspaper from above is greater than from below, and the rail breaks.

Notes: The rail must be laid so that its end of 10 cm hangs. The newspaper should fit snugly against the rail and the table.

Experience 6

Equipment: tripod with two clutches and legs, two demonstration dynamometers.

Conduct: We will fix two dynamometers on a tripod - a device for measuring force. Why are their readings the same? What does this mean?

Explanation: bodies act on each other with forces equal in magnitude and opposite in direction. (Newton's third law).

Experience 7

Equipment: two sheets of paper of the same size and weight (one of them is crumpled).

Implementation: Release both sheets at the same time from the same height. Why does a crumpled sheet of paper fall faster?

Explanation: A crumpled sheet of paper falls faster because there is less air resistance acting on it.

But in a vacuum, they would fall at the same time.

Experience 8 "How quickly the candle goes out"

Equipment: a glass vessel with water, a stearin candle, a nail, matches.

Conduct: Light a candle and lower it into a vessel of water. How fast will the candle go out?

Explanation: It seems that the flame will be filled with water as soon as the segment of the candle that protrudes above the water burns out and the candle goes out.

But, burning down, the candle decreases in weight and floats under the action of the Archimedean force.

Note: Attach a small weight (nail) to the bottom of the candle so that it floats in the water.

Experience 9 "Fireproof paper"

Equipment: metal rod, strip of paper, matches, candle (spirit lamp)

Conduct: Wrap the rod tightly with a strip of paper and bring it into the flame of a candle or spirit lamp. Why doesn't paper burn?

Explanation: Iron, being a good conductor of heat, removes heat from paper so it does not catch fire.

Experience 10 "Fireproof scarf"

Equipment: tripod with clutch and foot, alcohol, handkerchief, matches.

Implementation: Clamp a handkerchief (previously moistened with water and wrung out) in the foot of the tripod, douse it with alcohol and set it on fire. Despite the flame engulfing the handkerchief, it will not burn. Why?

Explanation: The heat released during the combustion of alcohol completely went to the evaporation of water, so it cannot ignite the fabric.

Experience 11 "Fireproof thread"

Equipment: a tripod with a clutch and a foot, a feather, a regular thread and a thread soaked in a saturated solution of table salt.

Conduct: We hang a feather on a thread and set it on fire. The thread burns out, and the feather falls. And now let's hang a feather on a magic thread and set it on fire. As you can see, the magic thread burns out, but the feather remains hanging. Explain the secret of the magic thread.

Explanation: The magic thread was soaked in a salt solution. When the thread is burned, the feather is held on by fused salt crystals.

Note: The thread should be soaked 3-4 times in a saturated salt solution.

Experience 12 "Water boils in a paper pot"

Equipment: a tripod with a clutch and a foot, a paper saucepan on threads, a spirit lamp, matches.

Conduct: Hang a paper pan on a tripod.

Can you boil water in this pot?

Explanation: All the heat released during combustion goes to heat the water. In addition, the temperature of the paper pot does not reach the ignition temperature.

Interesting questions.

Teacher: While the water boils, you can ask the audience questions:

What grows upside down? (icicle)

Bathed in water, but remained dry. (Goose, duck)

Why don't waterfowl get wet in the water? (The surface of their feathers is covered with a thin layer of fat, and water does not wet the oily surface.)

From the ground and the child will lift, but over the fence and the strongman will not throw. (Fluff)

During the day the window is broken, at night it is inserted. (hole)

The results of the experiments are summed up.

Grading.

2015-

1

1. Theory and methods of teaching physics at school. General issues. Ed. S.E. Kamenetsky, N.S. Purysheva. M.: Publishing Center "Academy", 2000.

2. Experiments and observations in physics homework. S.F. Pokrovsky. Moscow, 1963.

3. Perelman Ya.I. collection of entertaining books (29 pcs.). Quantum. Year of publication: 1919-2011.

"Tell me and I will forget, show me and I will remember, let me try and I will learn."

ancient chinese proverb

One of the main components of providing an information and educational environment for the subject of physics is educational resources and the correct organization of educational activities. A modern student who easily navigates the Internet can use various educational resources: http://sites.google.com/site/physics239/poleznye-ssylki/sajty, http://www.fizika.ru, http://www .alleng.ru/edu/phys, http://www.int-edu.ru/index.php, http://class-fizika.narod.ru, http://www.globallab.ru, http:/ /barsic.spbu.ru/www/edu/edunet.html, http://www.374.ru/index.php?x=2007-11-13-14, etc. Today, the main task of a teacher is to teach students to learn, to strengthen their ability to self-development in the process of education in the modern information environment.

The study of physical laws and phenomena by students should always be reinforced by a practical experiment. To do this, you need the appropriate equipment, which is in the physics classroom. The use of modern technology in the educational process makes it possible to replace a visual practical experiment with a computer model. On the site http://www.youtube.com (search for "experiments in physics") experiments carried out in real conditions are laid out.

An alternative to using the Internet can be an independent educational experiment that a student can conduct outside of school: on the street or at home. It is clear that experiments given at home should not use complex training devices, as well as investments in material costs. These can be experiments with air, water, with various objects that are available to the child. Of course, the scientific nature and value of such experiments is minimal. But if a child himself can check the law or phenomenon discovered many years before him, this is simply priceless for the development of his practical skills. Experience is a creative task and having done something on their own, the student, whether he wants it or not, will think: how easier it is to conduct an experiment where he met with a similar phenomenon in practice, where this phenomenon can still be useful.

What does a child need to conduct an experiment at home? First of all, this is a fairly detailed description of the experience, indicating the necessary items, where it is said in an accessible form for the student what needs to be done, what to pay attention to. In school physics textbooks for homework, it is proposed to either solve problems or answer the questions posed at the end of the paragraph. It is rare to find a description of an experience that is recommended for schoolchildren to conduct independently at home. Therefore, if the teacher invites the students to do something at home, then he is obliged to give them detailed instructions.

For the first time, home experiments and observations in physics began to be carried out in the 1934/35 academic year by Pokrovsky S.F. at school No. 85 in the Krasnopresnensky district of Moscow. Of course, this date is conditional, even in ancient times, teachers (philosophers) could advise their students to observe natural phenomena, test any law or hypothesis in practice at home. In his book S.F. Pokrovsky showed that home experiments and observations in physics carried out by the students themselves: 1) make it possible for our school to expand the area of ​​connection between theory and practice; 2) develop students' interest in physics and technology; 3) awaken creative thought and develop the ability to invent; 4) accustom students to independent research work; 5) develop valuable qualities in them: observation, attention, perseverance and accuracy; 6) supplement classroom laboratory work with material that cannot be done in class (a series of long-term observations, observation of natural phenomena, etc.); 7) accustom students to conscious, expedient work.

In the textbooks "Physics-7", "Physics-8" (authors A.V. Peryshkin), after studying certain topics, students are offered experimental tasks for observations that can be performed at home, explain their results, and compile a brief report on the work.

Since one of the requirements for home experience is ease of implementation, therefore, it is advisable to use them at the initial stage of teaching physics, when natural curiosity has not yet died out in children. It is difficult to come up with experiments for home use on such topics as, for example: most of the topic "Electrodynamics" (except for electrostatics and the simplest electrical circuits), "Physics of the atom", "Quantum physics". On the Internet, you can find a description of home experiments: http://adalin.mospsy.ru/l_01_00/op13.shtml, http://ponomari-school.ucoz.ru/index/0-52, http://ponomari-school .ucoz.ru/index/0-53, http://elkin52.narod.ru/opit/opit.htm, http://festival. 1september.ru/articles/599512 and others. I have prepared a selection of home experiments with brief instructions for implementation.

Home experiments in physics represent an educational type of activity for students, which allows not only to solve the educational and methodological educational tasks of the teacher, but also allows the student to see that physics is not only a subject of the school curriculum. The knowledge gained in the lesson is something that can really be used in life both from the point of view of practicality, and for evaluating some parameters of bodies or phenomena, and for predicting the consequences of any actions. Well, is 1 dm3 a lot or a little? Most students (and adults too) find it difficult to answer this question. But one has only to remember that a volume of 1 dm3 has an ordinary package of milk, and it immediately becomes easier to estimate the volumes of bodies: after all, 1 m3 is a thousand such bags! It is on such simple examples that understanding of physical quantities comes. When performing laboratory work, students work out their computational skills, and from their own experience they are convinced of the validity of the laws of nature. No wonder Galileo Galilei argued that science is true when it becomes clear even to the uninitiated. So home experiments are an extension of the information and educational environment of the modern student. After all, the life experience acquired over the years by trial and error is nothing more than elementary knowledge of physics.

The simplest measurements.

Exercise 1.

Once you have learned how to use a ruler and tape measure or tape measure in class, use these tools to measure the lengths of the following objects and distances:

a) the length of the index finger; b) the length of the elbow, i.e. distance from the end of the elbow to the end of the middle finger; c) the length of the foot from the end of the heel to the end of the big toe; d) neck circumference, head circumference; e) the length of a pen or pencil, a match, a needle, the length and width of a notebook.

Record the data obtained in a notebook.

Task 2.

Measure your height:

1. In the evening, before going to bed, take off your shoes, stand with your back to the door frame and lean firmly. Keep your head straight. Have someone use a square to make a small line on the jamb with a pencil. Measure the distance from the floor to the marked dash with a tape measure or centimeter. Express the measurement result in centimeters and millimeters, write it down in a notebook with the date (year, month, day, hour).

2. Do the same in the morning. Record the result again and compare the results of the evening and morning measurements. Bring the note to class.

Task 3.

Measure the thickness of a sheet of paper.

Take a book a little more than 1 cm thick and, opening the top and bottom covers of the cover, attach a ruler to the stack of paper. Pick up a stack of thickness 1 cm = 10 mm = 10,000 microns. Divide 10,000 microns by the number of sheets to express the thickness of one sheet in microns. Write down the result in a notebook. Think about how you can increase the accuracy of the measurement?

Task 4.

Determine the volume of a matchbox, a rectangular eraser, a juice or milk bag. Measure the length, width and height of the matchbox in millimeters. Multiply the resulting numbers, i.e. find the volume. Express the result in cubic millimeters and in cubic decimeters (liters), write it down. Make measurements and calculate the volumes of other proposed bodies.

Task 5.

Take a watch with a second hand (you can use an electronic watch or a stopwatch) and, looking at the second hand, watch it move for one minute (on an electronic watch, watch the digital values). Next, ask someone to mark aloud the beginning and end of a minute on the clock, while you yourself close your eyes at this time, and with your eyes closed perceive the duration of one minute. Do the opposite: standing with your eyes closed, try to set the length of one minute. Let the other person check you by the clock.

Task 6.

Learn to quickly find your pulse, then take a watch with a second hand or electronic and set how many beats of the pulse are observed in one minute. Then do the reverse work: counting the pulse beats, set the duration to one minute (entrust the watch to another person)

Note. The great scientist Galileo, observing the swinging of the chandelier in the Florence Cathedral and using (instead of a clock) the beating of his own pulse, established the first law of pendulum oscillation, which formed the basis of the doctrine of oscillatory motion.

Task 7.

Using a stopwatch, set as accurately as possible the number of seconds in which you run a distance of 60 (100) m. Divide the path by the time, i.e. Determine the average speed in meters per second. Convert meters per second to kilometers per hour. Write down the results in a notebook.

Pressure.

Exercise 1.

Determine the pressure produced by the stool. Place a piece of checkered paper under the leg of the chair, circle the leg with a sharpened pencil and, taking out the piece of paper, count the number of square centimeters. Calculate the area of ​​support for the four legs of the chair. Think about how else you can calculate the area of ​​\u200b\u200bthe support of the legs?

Find out your weight along with the chair. This can be done using scales designed to weigh people. To do this, you need to pick up a chair and stand on the scales, i.e. weigh yourself along with the chair.

If for some reason it is impossible to find out the mass of the chair you have, take the mass of the chair equal to 7 kg (average mass of chairs). Add your average stool weight to your own body weight.

Count your weight with the chair. To do this, the sum of the masses of a chair and a person must be multiplied by about ten (more precisely, by 9.81 m/s2). If the mass was in kilograms, then you get the weight in newtons. Using the formula p = F/S, calculate the pressure of the chair on the floor if you are sitting in the chair without your feet touching the floor. Record all measurements and calculations in a notebook and bring to class.

Task 2.

Fill the glass with water up to the rim. Cover the glass with a sheet of thick paper and, holding the paper with your palm, quickly turn the glass upside down. Now remove your hand. The water will not spill out of the glass. The pressure of atmospheric air on a piece of paper is greater than the pressure of water on it.

Just in case, do all this over the basin, because with a slight skew of the paper and with insufficient experience at first, water can be spilled.

Task 3.

"Diving bell" is a large metal cap, which is lowered with the open side to the bottom of the reservoir for the performance of any work. After lowering it into the water, the air contained in the cap is compressed and does not let water into this device. Only at the very bottom remains a little water. In such a bell, people can move and perform the work entrusted to them. Let's make a model of this device.

Take a glass and a plate. Pour water into a plate and place a glass turned upside down in it. The air in the glass will compress, and the bottom of the plate under the glass will be filled with very little water. Before you put a glass in a plate, put a cork on the water. It will show how little water is left at the bottom.

Task 4.

This entertaining experience is about three hundred years old. It is attributed to the French scientist René Descartes (in Latin, his surname is Cartesius). The experience was so popular that they created the Carthusian Diver toy based on it. We can do this experience with you. To do this, you will need a plastic bottle with a cork, a pipette and water. Fill the bottle with water, leaving two to three millimeters to the edge of the neck. Take a pipette, draw some water into it and lower it into the neck of the bottle. It should be at or slightly above the level of the water in the bottle with its upper rubber end. In this case, it is necessary to achieve that, from a slight push with a finger, the pipette sinks, and then slowly rises up by itself. Now close the cork and squeeze the sides of the bottle. The pipette will go to the bottom of the bottle. Release the pressure on the bottle and it will pop up again. The fact is that we slightly compressed the air in the neck of the bottle and this pressure was transferred to the water. Water penetrated into the pipette - it became heavier and drowned. When the pressure was released, the compressed air inside the pipette removed the excess water, our "diver" became lighter and floated. If at the beginning of the experiment the “diver” does not obey you, then you need to adjust the amount of water in the pipette.

When the pipette is at the bottom of the bottle, it is easy to see how water enters the pipette from increased pressure on the walls of the bottle, and exits from it when the pressure is released.

Task 5.

Make a fountain known in the history of physics as Heron's fountain. Pass a piece of glass tube with a drawn end through a cork inserted into a thick-walled bottle. Fill the bottle with as much water as needed to submerge the end of the tube in the water. Now, in two or three steps, blow air into the bottle with your mouth, clamping the end of the tube after each blow. Release your finger and watch the fountain.

If you want to get a very strong fountain, then use a bicycle pump to pump air. However, remember that with more than one or two strokes of the pump, the cork can fly out of the bottle and you will need to hold it with your finger, and with a very large number of strokes, compressed air can break the bottle, so you need to use the pump very carefully.

Law of Archimedes.

Exercise 1.

Prepare a wooden stick (twig), a wide jar, a bucket of water, a wide vial with a cork and a rubber thread at least 25 cm long.

1. Push the stick into the water and watch it pop out of the water. Do this several times.

2. Push the can upside down into the water and watch it pop out of the water. Do this several times. Remember how difficult it is to push a bucket upside down into a barrel of water (if you have not observed this, do it at any opportunity).

3. Fill the bottle with water, close the cork and tie a rubber thread to it. Holding the thread by the free end, watch how it shortens as the bubble is immersed in water. Do this several times.

4. A tin plate sinks on water. Bend the edges of the plate so that you get a box. Put her on the water. She swims. Instead of a tin plate, you can use a piece of foil, preferably rigid. Make a foil box and put it on the water. If the box (of foil or metal) does not leak, then it will float on the surface of the water. If the box takes on water and sinks, think about how to fold it in such a way that water does not get inside.

Describe and explain these phenomena in your notebook.

Task 2.

Take a piece of shoe pitch or wax the size of an ordinary hazelnut, make a regular ball out of it and with a small load (insert a piece of wire) make it smoothly sink in a glass or test tube with water. If the ball sinks without load, then, of course, it should not be loaded. In the absence of var or wax, you can cut a small ball from the pulp of a raw potato.

Pour a little saturated solution of pure table salt into the water and mix lightly. First make sure that the ball is kept in balance in the middle of the glass or test tube, and then that it floats to the surface of the water.

Note. The proposed experiment is a variant of the well-known experiment with a chicken egg and has a number of advantages over the last experiment (it does not require a freshly laid chicken egg, a large tall vessel and a large amount of salt).

Task 3.

Take a rubber ball, a table tennis ball, pieces of oak, birch and pine wood and let them float on the water (in a bucket or basin). Carefully observe the swimming of these bodies and determine by eye what part of these bodies sinks into the water when swimming. Remember how deep a boat, a log, an ice floe, a ship, and so on, sinks into the water.

Forces of surface tension.

Exercise 1.

Prepare a glass plate for this experiment. Wash it well with soap and warm water. When it dries, wipe one side with a cotton swab dipped in cologne. Do not touch its surface with anything, and now you need to take the plate only by the edges.

Take a piece of smooth white paper and drip stearin from a candle onto it to make a flat, flat stearin plate the size of the bottom of a glass.

Place stearin and glass plates side by side. Put a small drop of water on each of them from a pipette. On a stearin plate, a hemisphere with a diameter of about 3 millimeters will be obtained, and on a glass plate a drop will spread. Now take a glass plate and tilt it. The drop has already spread, and now it will flow further. Water molecules are more readily attracted to glass than to each other. Another drop will roll on the stearin when the plate is tilted in different directions. Water cannot stay on stearin, it does not wet it, water molecules are attracted to each other more strongly than to stearin molecules.

Note. In the experiment, carbon black can be used instead of stearin. It is necessary to drop water from a pipette onto the sooty surface of a metal plate. The drop will turn into a ball and quickly roll over the soot. So that the next drops do not immediately roll off the plate, you need to keep it strictly horizontal.

Task 2.

The blade of a safety razor, despite the fact that it is steel, can float on the surface of the water. Just make sure it doesn't get wet with water. To do this, it needs to be lightly greased. Place the blade carefully on the surface of the water. Place a needle across the blade, and one button at the end of the blade. The load will turn out to be quite solid, and you can even see how the razor is pressed into the water. It seems as if there is an elastic film on the surface of the water, which holds such a load on itself.

You can also make the needle float by first lubricating it with a thin layer of fat. It must be placed on the water very carefully so as not to pierce the surface layer of water. It may not work right away, it will take some patience and practice.

Pay attention to how the needle is located on the water. If the needle is magnetized, then it is a floating compass! And if you take a magnet, you can make the needle travel through the water.

Task 3.

Place two identical pieces of cork on the surface of clean water. Bring them together with the tips of a match. Please note: as soon as the distance between the plugs decreases to half a centimeter, this water gap between the plugs will shrink itself, and the plugs will quickly attract each other. But traffic jams tend not only to each other. They are well attracted to the edge of the dishes in which they swim. To do this, you just need to bring them closer to him at a short distance.

Try to explain what you see.

Task 4.

Take two glasses. Fill one of them with water and put it higher. Another glass, empty, put below. Dip the end of a strip of clean matter into a glass of water, and its other end into the bottom glass. Water, taking advantage of the narrow gaps between the fibers of matter, will begin to rise, and then, under the influence of gravity, will flow into the lower glass. So a strip of matter can be used as a pump.

Task 5.

This experiment (Plato's experiment) clearly shows how, under the action of surface tension forces, a liquid turns into a ball. For this experiment, alcohol is mixed with water in such a ratio that the mixture has the density of an oil. Pour this mixture into a glass vessel and introduce vegetable oil into it. The oil is immediately located in the middle of the vessel, forming a beautiful, transparent, yellow ball. For the ball, such conditions are created as if it were in zero gravity.

To do the Plateau experiment in miniature, you need to take a very small transparent vial. It should contain a little sunflower oil - about two tablespoons. The fact is that after the experience, the oil will become completely unusable, and the products must be protected.

Pour some sunflower oil into the prepared vial. Take a thimble as a dish. Drop a few drops of water and the same amount of cologne into it. Stir the mixture, draw it into a pipette and release one drop into the oil. If the drop, becoming a ball, goes to the bottom, then the mixture turned out to be heavier than oil, it must be lightened. To do this, add one or two drops of cologne to the thimble. Cologne is made from alcohol and is lighter than water and oil. If the ball from the new mixture does not start to fall, but, on the contrary, rises, it means that the mixture has become lighter than oil and a drop of water should be added to it. So, by alternating the addition of water and cologne in small, drop doses, it is possible to achieve that a ball of water and cologne will “hang” in oil at any level. The classic Plato experience in our case looks the other way around: the oil and the mixture of alcohol and water are reversed.

Note. Experience can be given at home and when studying the topic "Law of Archimedes".

Task 6.

How to change the surface tension of water? Pour clean water into two bowls. Take scissors and cut two narrow strips one square wide from a sheet of paper into a box. Take one strip and, holding it over one plate, cut off pieces from the strip one by one, trying to do it so that the pieces falling into the water are located on the water in a ring in the middle of the plate and do not touch each other or the edges of the plate.

Take a bar of soap with a pointed end and touch the pointed end to the surface of the water in the middle of the paper ring. What are you watching? Why do pieces of paper start to scatter?

Now take another strip, also cut off several pieces of paper from it over another plate and, touching a piece of sugar to the middle of the surface of the water inside the ring, keep it in the water for some time. The pieces of paper will come closer to each other, gathering.

Answer the question: how did the surface tension of water change from the admixture of soap to it and from the admixture of sugar?

Exercise 1.

Take a long heavy book, tie it with a thin thread and attach a rubber thread 20 cm long to the thread.

Put the book on the table and very slowly begin to pull on the end of the rubber thread. Try to measure the length of the stretched rubber thread at the moment the book begins to slide.

Measure the length of the stretched book with the book moving evenly.

Place two thin cylindrical pens (or two cylindrical pencils) under the book and pull the end of the thread in the same way. Measure the length of the stretched thread with a uniform movement of the book on the rollers.

Compare the three results and draw conclusions.

Note. The next task is a variation of the previous one. It also aims to compare static friction, sliding friction, and rolling friction.

Task 2.

Place a hexagonal pencil on top of the book parallel to the spine. Slowly lift the top edge of the book until the pencil begins to slide down. Slightly reduce the slope of the book and secure it in this position by placing something under it. Now the pencil, if you put it on the book again, will not move out. It is held in place by the force of friction - the force of static friction. But it is worth weakening this force a little - and for this it is enough to click on the book with your finger - and the pencil will crawl down until it falls on the table. (The same experiment can be done, for example, with a pencil case, a matchbox, an eraser, etc.)

Think about why it is easier to pull a nail out of the board if you rotate it around its axis?

To move a thick book on the table with one finger, you need to make some effort. And if you put two round pencils or pens under the book, which in this case will be roller bearings, the book will easily move from a slight push with your little finger.

Do experiments and compare the force of static friction, the force of sliding friction and the force of rolling friction.

Task 3.

In this experiment, two phenomena can be observed at once: inertia, experiments with which will be described later, and friction.

Take two eggs, one raw and one hard boiled. Roll both eggs on a large plate. You can see that a boiled egg behaves differently than a raw one: it spins much faster.

In a boiled egg, the protein and yolk are rigidly connected to their shell and to each other. are in a solid state. And when we spin a raw egg, we first spin only the shell, only then, due to friction, layer by layer, the rotation is transferred to the protein and yolk. Thus, liquid protein and yolk, by their friction between the layers, inhibit the rotation of the shell.

Note. Instead of raw and boiled eggs, you can spin two pans, one of which contains water, and the other contains the same amount of cereal.

Center of gravity.

Exercise 1.

Take two faceted pencils and hold them in front of you parallel, putting a ruler on them. Start bringing the pencils closer together. Rapprochement will occur in successive movements: then one pencil moves, then the other. Even if you want to interfere with their movement, you will not succeed. They will still move forward.

As soon as there is more pressure on one pencil and the friction has increased so much that the pencil cannot move any further, it stops. But the second pencil can now move under the ruler. But after a while, the pressure above it also becomes greater than above the first pencil, and due to increased friction, it stops. And now the first pencil can move. So, moving in turn, the pencils will meet in the very middle of the ruler at its center of gravity. This can be easily verified by the divisions of the ruler.

This experiment can also be done with a stick, holding it on outstretched fingers. As you move your fingers, you will notice that they, also moving alternately, will meet under the very middle of the stick. True, this is only a special case. Try doing the same with a regular broom, shovel, or rake. You will see that the fingers will not meet in the middle of the stick. Try to explain why this is happening.

Task 2.

This is an old, very visual experience. Penknife (folding) you probably have a pencil too. Sharpen the pencil so that it has a sharp end, and stick a half-open penknife a little higher than the end. Place the tip of the pencil on your index finger. Find such a position of the half-open knife on the pencil, in which the pencil will stand on the finger, swaying slightly.

Now the question is: where is the center of gravity of the pencil and penknife?

Task 3.

Determine the position of the center of gravity of a match with and without a head.

Place a matchbox on the table on its long narrow edge and place a match without a head on the box. This match will serve as a support for another match. Take a match with a head and balance it on a support so that it lies horizontally. With a pen, mark the position of the center of gravity of the match with the head.

Scrape off the head of the match and place the match on the support so that the ink dot you marked lies on the support. Now you will not be able to do this: the match will not lie horizontally, since the center of gravity of the match has moved. Determine the position of the new center of gravity and note which way it has moved. Mark the center of gravity of the headless match with a pen.

Bring a match with two dots to class.

Task 4.

Determine the position of the center of gravity of a flat figure.

Cut out a figure of arbitrary (some fancy) shape from cardboard and pierce several holes in various arbitrary places (it is better if they are located closer to the edges of the figure, this will increase accuracy). Drive a small nail without a hat or a needle into a vertical wall or rack and hang a figure on it through any hole. Pay attention: the figure should swing freely on the stud.

Take a plumb line, consisting of a thin thread and a weight, and throw its thread over a stud so that it indicates the vertical direction of an unsuspended figure. Mark the vertical direction of the thread on the figure with a pencil.

Remove the figure, hang it from any other hole, and again, using a plumb line and a pencil, mark on it the vertical direction of the thread.

The intersection point of the vertical lines will indicate the position of the center of gravity of this figure.

Pass a thread through the center of gravity you found, at the end of which a knot is made, and hang the figure on this thread. The figure should be held almost horizontally. The more accurately the experiment is done, the more horizontal the figure will be.

Task 5.

Determine the center of gravity of the hoop.

Take a small hoop (like a hoop) or make a ring out of a flexible twig, a narrow strip of plywood or hard cardboard. Hang it on a stud and lower the plumb line from the hanging point. When the plumb line calms down, mark on the hoop the points of its touch to the hoop and between these points pull and fasten a piece of thin wire or fishing line (you need to pull hard enough, but not so much that the hoop changes its shape).

Hang the hoop on a stud at any other point and do the same. The intersection point of the wires or lines will be the center of gravity of the hoop.

Note: the center of gravity of the hoop lies outside the substance of the body.

Tie a thread to the intersection of wires or lines and hang a hoop on it. The hoop will be in an indifferent equilibrium, since the center of gravity of the hoop and the point of its support (suspension) coincide.

Task 6.

You know that the stability of a body depends on the position of the center of gravity and on the size of the area of ​​support: the lower the center of gravity and the larger the area of ​​support, the more stable the body.

Keeping this in mind, take a bar or an empty matchbox and, placing it alternately on paper in a box on the widest, on the middle and on the smallest edge, circle each time with a pencil to get three different areas of support. Calculate the size of each area in square centimeters and put them on paper.

Measure and record the height of the center of gravity of the box for all three cases (the center of gravity of the matchbox lies at the intersection of the diagonals). Conclude at what position of the boxes is the most stable.

Task 7.

Sit on a chair. Place your feet upright without slipping them under the seat. Sit completely straight. Try to stand up without leaning forward, without stretching your arms forward, and without sliding your legs under the seat. You won't succeed - you won't be able to get up. Your center of gravity, which is somewhere in the middle of your body, will not let you stand up.

What condition must be met in order to get up? It is necessary to lean forward or tuck your legs under the seat. When we get up, we always do both. In this case, the vertical line passing through your center of gravity must necessarily pass through at least one of the feet of your legs or between them. Then the balance of your body will be stable enough, you can easily stand up.

Well, now try to stand up, picking up dumbbells or an iron. Stretch your arms forward. You may be able to stand up without bending over or bending your legs under you.

Exercise 1.

Put a postcard on the glass, and place a coin or checker on the postcard so that the coin is above the glass. Hit the card with a click. The postcard should fly out, and the coin (checker) should fall into the glass.

Task 2.

Place a double sheet of notebook paper on the table. Place a stack of books at least 25 cm high on one half of the sheet.

Slightly lifting the second half of the sheet above the level of the table with both hands, quickly pull the sheet towards you. The sheet should free itself from under the books, and the books should remain in place.

Put the book back on the sheet and pull it now very slowly. The books will move along with the sheet.

Task 3.

Take a hammer, tie a thin thread to it, but so that it can withstand the weight of the hammer. If one thread fails, take two threads. Slowly lift the hammer up by the thread. The hammer will hang on a thread. And if you want to pick it up again, but not slowly, but with a quick jerk, the thread will break (make sure that the hammer, when falling, does not break anything under it). The inertia of the hammer is so great that the thread could not stand it. The hammer did not have time to quickly follow your hand, remained in place, and the thread broke.

Task 4.

Take a small ball made of wood, plastic or glass. Make a groove out of thick paper, put a ball in it. Move the groove across the table quickly and then suddenly stop it. By inertia, the ball will continue to move and roll, jumping out of the groove. Check where the ball will roll if:

a) pull the chute very quickly and stop it abruptly;

b) pull the chute slowly and stop abruptly.

Task 5.

Cut the apple in half, but not all the way through, and let it hang on the knife.

Now hit the blunt side of the knife with the apple hanging on top of it on something hard, such as a hammer. The apple, continuing to move by inertia, will be cut and split into two halves.

Exactly the same thing happens when wood is chopped: if it was not possible to split a block of wood, they usually turn it over and, with all their strength, hit the butt of the ax on a solid support. Churbak, continuing to move by inertia, is planted deeper on the ax and splits in two.

Exercise 1.

Put on the table, next to it, a wooden board and a mirror. Place a room thermometer between them. After some rather long time, we can assume that the temperatures of the wooden board and the mirror have become equal. The thermometer shows the air temperature. The same as, obviously, both the blackboard and the mirror.

Touch the mirror with your palm. You will feel the cold glass. Immediately touch the board. It will seem much warmer. What's the matter? After all, the temperature of the air, boards and mirrors is the same.

Why did glass seem colder than wood? Try to answer this question.

Glass is a good conductor of heat. As a good conductor of heat, the glass will immediately begin to heat up from your hand, and will eagerly “pump out” heat from it. From this you feel cold in the palm of your hand. Wood is a poor conductor of heat. It will also begin to "pump" heat into itself, heating up from the hand, but it does this much more slowly, so you do not feel a sharp cold. Here the tree seems to be warmer than glass, although both have the same temperature.

Note. Styrofoam can be used instead of wood.

Task 2.

Take two identical smooth glasses, pour boiling water into one glass up to 3/4 of its height and immediately cover the glass with a piece of porous (not laminated) cardboard. Place a dry glass upside down on the cardboard and watch how its walls gradually fog up. This experience confirms the properties of vapors to diffuse through partitions.

Task 3.

Take a glass bottle and cool it well (for example, putting it in the cold or putting it in the refrigerator). Pour water into a glass, mark the time in seconds, take a cold bottle and, holding it in both hands, lower your throat into the water.

Count how many air bubbles will come out of the bottle during the first minute, during the second and during the third minute.

Write down the results. Bring your work report to class.

Task 4.

Take a glass bottle, heat it well over water vapor and pour boiling water into it to the very top. Put the bottle like this on the windowsill and mark the time. After 1 hour, mark the new water level in the bottle.

Bring your work report to class.

Task 5.

Establish the dependence of the evaporation rate on the free surface area of ​​the liquid.

Fill a test tube (small bottle or vial) with water and pour onto a tray or flat plate. Fill the same container again with water and place next to the plate in a quiet place (for example, on a cupboard), allowing the water to evaporate calmly. Write down the start date of the experiment.

When the water on the plate has evaporated, mark and record the time again. See what part of the water has evaporated from the test tube (bottle).

Make a conclusion.

Task 6.

Take a tea glass, fill it with pieces of pure ice (for example, from a broken icicle) and bring the glass into the room. Pour room water into a glass up to the brim. When all the ice has melted, see how the water level in the glass has changed. Make a conclusion about the change in the volume of ice during melting and about the density of ice and water.

Task 7.

Watch the snow fall. Take half a glass of dry snow on a frosty day in winter and put it outside the house under some kind of canopy so that snow from the air does not get into the glass.

Write down the start date of the experiment and watch the snow sublimate. When all the snow is gone, write down the date again.

Write a report.

Topic: "Determining the average speed of a person."

Purpose: Using the speed formula, determine the speed of a person's movement.

Equipment: mobile phone, ruler.

Progress:

1. Use a ruler to determine the length of your step.

2. Walk around the apartment, counting the number of steps.

3. Using the mobile phone's stopwatch, determine the time of your movement.

4. Using the speed formula, determine the speed of movement (all quantities must be expressed in the SI system).

Topic: "Determination of the density of milk."

Purpose: to check the quality of the product by comparing the value of the tabular density of the substance with the experimental one.

Progress:

1. Measure the weight of the milk package using the control scales in the store (there must be a marking coupon on the package).

2. Use a ruler to determine the dimensions of the package: length, width, height, - convert the measurement data to the SI system and calculate the volume of the package.

4. Compare the obtained data with the tabulated density value.

5. Make a conclusion about the results of the work.

Topic: "Determining the weight of a package of milk."

Purpose: using the value of the tabular density of a substance, calculate the weight of a package of milk.

Equipment: milk carton, substance density table, ruler.

Progress:

1. With a ruler, determine the dimensions of the package: length, width, height, - convert the measurement data into the SI system and calculate the volume of the package.

2. Using the value of the table density of milk, determine the mass of the package.

3. Determine the package weight using the formula.

4. Graphically depict the linear dimensions of the package and its weight (two drawings).

5. Make a conclusion about the results of the work.

Topic: "Determining the pressure produced by a person on the floor"

Purpose: using the formula, determine the pressure of a person on the floor.

Equipment: floor scales, notebook sheet in a cage.

Progress:

1. Stand on a notebook sheet and circle your foot.

2. To determine the area of ​​your foot, count the number of full cells and separately - incomplete cells. Halve the number of incomplete cells, add the number of full cells to the result obtained, and divide the sum by four. This is the area of ​​one foot.

3. Using floor scales, determine the weight of your body.

4. Using the solid body pressure formula, determine the pressure exerted on the floor (all values ​​must be expressed in SI units). Don't forget that a person stands on two legs!

5. Make a conclusion about the results of the work. Attach a sheet with the outline of the foot to work.

Topic: "Checking the phenomenon of hydrostatic paradox".

Purpose: Using the general formula for pressure, determine the pressure of a liquid at the bottom of a vessel.

Equipment: measuring vessel, high-walled glass, vase, ruler.

Progress:

1. With a ruler, determine the height of the liquid poured into the glass and vase; it should be the same.

2. Determine the mass of liquid in a glass and a vase; To do this, use a measuring vessel.

3. Determine the area of ​​the bottom of the glass and vase; To do this, measure the diameter of the bottom with a ruler and use the formula for the area of ​​a circle.

4. Using the general formula for pressure, determine the pressure of the water at the bottom of the glass and vase (all values ​​must be expressed in SI units).

5. Illustrate the course of the experiment with a drawing.

Topic: "Determination of the density of the human body."

Purpose: using the Archimedes principle and the formula for calculating density, determine the density of the human body.

Equipment: liter jar, floor scales.

Progress:

4. Using a floor scale, determine your weight.

5. Using the formula, determine the density of your body.

6. Make a conclusion about the results of the work.

Topic: "Definition of Archimedean force".

Purpose: using the law of Archimedes, to determine the buoyancy force acting from the side of the liquid on the human body.

Equipment: liter jar, bath.

Progress:

1. Fill the bath with water, mark the water level along the edge.

2. Immerse yourself in a bath. This will increase the liquid level. Make a mark along the edge.

3. Using a liter jar, determine your volume: it is equal to the difference between the volumes marked along the edge of the bath. Convert your result to the SI system.

5. Illustrate the experiment performed by indicating the vector of Archimedes' force.

6. Make a conclusion based on the results of the work.

Topic: "Determining the conditions for swimming the body."

Purpose: Using the principle of Archimedes, determine the location of your body in a liquid.

Equipment: liter jar, floor scales, bath.

Progress:

1. Fill the bath with water, mark the water level along the edge.

2. Immerse yourself in a bath. This will increase the liquid level. Make a mark along the edge.

3. Using a liter jar, determine your volume: it is equal to the difference between the volumes marked along the edge of the bath. Convert your result to the SI system.

4. Using the law of Archimedes, determine the buoyant action of the liquid.

5. Use a floor scale to measure your weight and calculate your weight.

6. Compare your weight to the Archimedean force and locate your body in the fluid.

7. Illustrate the experiment performed by indicating the weight and force vectors of Archimedes.

8. Make a conclusion based on the results of the work.

Topic: "Definition of work to overcome the force of gravity."

Purpose: using the work formula, determine the physical load of a person when making a jump.

Progress:

1. Use a ruler to determine the height of your jump.

3. Using the formula, determine the work required to complete the jump (all quantities must be expressed in SI units).

Topic: "Determining the landing speed."

Purpose: using the formulas of kinetic and potential energy, the law of conservation of energy, determine the landing speed when making a jump.

Equipment: floor scales, ruler.

Progress:

1. Use a ruler to determine the height of the chair from which the jump will be made.

2. Use a floor scale to determine your weight.

3. Using the formulas of kinetic and potential energy, the law of conservation of energy, derive a formula for calculating the landing speed when making a jump and perform the necessary calculations (all quantities must be expressed in the SI system).

4. Make a conclusion about the results of the work.

Topic: "Mutual attraction of molecules"

Equipment: cardboard, scissors, a bowl of cotton wool, dishwashing liquid.

Progress:

1. Cut out a boat in the form of a triangular arrow from cardboard.

2. Pour water into a bowl.

3. Carefully place the boat on the surface of the water.

4. Dip your finger in dishwashing liquid.

5. Gently dip your finger into the water just behind the boat.

6. Describe observations.

7. Make a conclusion.

Topic: "How different fabrics absorb moisture"

Equipment: different shreds of fabric, water, a tablespoon, a glass, a rubber band, scissors.

Progress:

1. Cut out a 10x10 cm square from various pieces of fabric.

2. Cover the glass with these pieces.

3. Fix them on the glass with a rubber band.

4. Carefully pour a spoonful of water on each piece.

5. Remove the flaps, pay attention to the amount of water in the glass.

6. Draw conclusions.

Topic: "Mixing Immiscibles"

Equipment: a plastic bottle or a transparent disposable glass, vegetable oil, water, a spoon, dishwashing liquid.

Progress:

1. Pour some oil and water into a glass or bottle.

2. Thoroughly mix oil and water.

3. Add some dishwashing liquid. Stir.

4. Describe observations.

Topic: "Determining the distance traveled from home to school"

Progress:

1. Select a route.

2. Approximately calculate the length of one step using a tape measure or centimeter tape. (S1)

3. Calculate the number of steps while moving along the selected route (n).

4. Calculate the length of the path: S = S1 · n, in meters, kilometers, fill in the table.

5. Draw the route to scale.

6. Make a conclusion.

Topic: "Interaction of bodies"

Equipment: glass, cardboard.

Progress:

1. Put the glass on the cardboard.

2. Slowly pull on the cardboard.

3. Quickly pull out the cardboard.

4. Describe the movement of the glass in both cases.

5. Make a conclusion.

Topic: "Calculating the density of a bar of soap"

Equipment: a piece of laundry soap, a ruler.

Progress:

3. Using a ruler, determine the length, width, height of the piece (in cm)

4. Calculate the volume of a bar of soap: V = a b c (in cm3)

5. Using the formula, calculate the density of a bar of soap: p \u003d m / V

6. Fill in the table:

7. Convert the density, expressed in g / cm 3, to kg / m 3

8. Make a conclusion.

Topic: "Is air heavy?"

Equipment: two identical balloons, a wire hanger, two clothespins, a pin, a thread.

Progress:

1. Inflate two balloons to a single size and tie with a thread.

2. Hang the hanger on the rail. (You can put a stick or mop on the backs of two chairs and attach a hanger to it.)

3. Attach a balloon to each end of the hanger with a clothespin. Balance.

4. Pierce one ball with a pin.

5. Describe the observed phenomena.

6. Make a conclusion.

Topic: "Determination of mass and weight in my room"

Equipment: tape measure or measuring tape.

Progress:

1. Using a tape measure or measuring tape, determine the dimensions of the room: length, width, height, expressed in meters.

2. Calculate the volume of the room: V = a b c.

3. Knowing the air density, calculate the mass of air in the room: m = p·V.

4. Calculate the weight of air: P = mg.

5. Fill in the table:

6. Make a conclusion.

Theme: "Feel the Friction"

Equipment: dishwashing liquid.

Progress:

1. Wash your hands and dry them dry.

2. Quickly rub your palms together for 1-2 minutes.

3. Apply some dishwashing liquid to your palms. Rub your palms again for 1-2 minutes.

4. Describe the observed phenomena.

5. Make a conclusion.

Topic: "Determining the dependence of gas pressure on temperature"

Equipment: balloon, thread.

Progress:

1. Inflate the balloon, tie it with a thread.

2. Hang the ball outside.

3. After a while, pay attention to the shape of the ball.

4. Explain why:

a) By directing a stream of air when inflating the balloon in one direction, we make it inflate in all directions at once.

b) Why do not all balls take on a spherical shape.

c) Why does the ball change its shape when the temperature is lowered?

5. Make a conclusion.

Topic: "Calculation of the force with which the atmosphere presses on the surface of the table?"

Equipment: measuring tape.

Progress:

1. Using a tape measure or measuring tape, calculate the length and width of the table, expressed in meters.

2. Calculate the area of ​​the table: S = a b

3. Take the pressure from the atmosphere equal to Rat = 760 mm Hg. translate Pa.

4. Calculate the force acting from the atmosphere on the table:

P = F/S; F = P S; F = P a b

5. Fill in the table.

6. Make a conclusion.

Topic: "Floats or sinks?"

Equipment: large bowl, water, paper clip, apple slice, pencil, coin, cork, potato, salt, glass.

Progress:

1. Pour water into a bowl or basin.

2. Carefully lower all the listed items into the water.

3. Take a glass of water, dissolve 2 tablespoons of salt in it.

4. Dip into the solution those objects that drowned in the first.

5. Describe observations.

6. Make a conclusion.

Topic: "Calculation of the work done by the student when lifting from the first to the second floor of a school or house"

Equipment: tape measure.

Progress:

1. Using a tape measure, measure the height of one step: So.

2. Calculate the number of steps: n

3. Determine the height of the stairs: S = So n.

4. If possible, determine the weight of your body, if not, take approximate data: m, kg.

5. Calculate the gravity of your body: F = mg

6. Determine the work: A = F S.

7. Fill in the table:

8. Make a conclusion.

Topic: "Determination of the power that a student develops, evenly rising slowly and quickly from the first to the second floor of a school or house"

Equipment: data of the work “Calculation of the work done by the student when lifting from the first to the second floor of a school or house”, stopwatch.

Progress:

1. Using the data of the work "Calculation of the work done by the student when climbing from the first to the second floor of a school or house" determine the work done when climbing the stairs: A.

2. Using a stopwatch, determine the time taken to slowly climb the stairs: t1.

3. Using a stopwatch, determine the time taken to quickly climb the stairs: t2.

4. Calculate the power in both cases: N1, N2, N1 = A/ t1, N2 = A/t2

5. Record the results in a table:

6. Make a conclusion.

Topic: "Clarification of the equilibrium condition of the lever"

Equipment: ruler, pencil, rubber band, old-style coins (1 k, 2 k, 3 k, 5 k).

Progress:

1. Place a pencil under the middle of the ruler so that the ruler is in balance.

2. Put an elastic band on one end of the ruler.

3. Balance the lever with coins.

4. Taking into account that the mass of coins of the old sample is 1 k - 1 g, 2 k - 2 g, 3 k - 3 g, 5 k - 5 g. Calculate the mass of the gum, m1, kg.

5. Move the pencil to one of the ends of the ruler.

6. Measure the shoulders l1 and l2, m.

7. Balance the lever with coins m2, kg.

8. Determine the forces acting on the ends of the lever F1 = m1g, F2 = m2g

9. Calculate the moment of forces M1 = F1l1, M2 = P2l2

10. Fill in the table.

11. Make a conclusion.

Bibliographic link

Vikhareva E.V. HOME EXPERIMENTS IN PHYSICS GRADES 7–9 // Start in science. - 2017. - No. 4-1. - P. 163-175;
URL: http://science-start.ru/ru/article/view?id=702 (date of access: 21.02.2019).