Physics experience hand trap. Experiments in physics
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 a physics subject is educational resources and the correct organization of educational activities. A modern student who can easily navigate 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 the teacher is to teach students how to learn, to strengthen their ability for 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 practical experiment. This requires the appropriate equipment, which is in the physics room. The use of modern technology in the educational process allows you to replace a visual practical experiment with a computer model. The site http://www.youtube.com (search for "physics experiments") contains experiments carried out in real conditions.
An alternative to using the Internet can be an independent educational experiment that the student can conduct outside of school: on the street or at home. It is unambiguous that experiments that are asked at home should not use complex teaching 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 a 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 his own, the student, whether he wants it or not, will think about 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 have an experience at home? First of all, this is a fairly detailed description of the experience, indicating the necessary subjects, where it is said in an accessible form for the student what to do, what to pay attention to. In school physics textbooks, it is suggested either to solve problems at home, or to answer the questions posed at the end of the paragraph. It is rare to find there a description of an experience that is recommended for schoolchildren to conduct at home on their own. Therefore, if the teacher invites 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 S.F. at school number 85 Krasnopresnensky district of Moscow. Of course, this date is conditional; even in antiquity, teachers (philosophers) could advise their students to observe natural phenomena, to 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) teach 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 performed in the classroom in any way (a series of long-term observations, observation of natural phenomena, etc.); 7) teach students to conscious, purposeful 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 draw up a short report on the work.
Since one of the requirements for home experience is simplicity in implementation, therefore, their application is advisable to carry out 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 topics such 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, etc. I have prepared a selection of home experiments with short instructions for implementation.
Home experiments in physics represent an educational type of student activity, which allows not only to solve the teaching 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 the volume of 1 dm3 has a regular carton of milk, and it immediately becomes easier to estimate the volume of bodies: after all, 1 m3 is a thousand such bags! It is on such simple examples that the understanding of physical quantities comes. When performing laboratory work, students practice computational skills, 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 experiences are an extension of the information and educational environment of the modern student. After all, life experience acquired over the years by trial and error is nothing more than elementary knowledge of physics.
The simplest measurements.
Exercise 1.
Having learned how to use a ruler and tape measure or a centimeter in class, measure the lengths of the following objects and distances with these devices:
a) the length of the index finger; b) the length of the elbow, i.e. the 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, matches, needles, the length and width of the notebook.
Write down the received data 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 place a small pencil line on the jamb. Measure the distance from the floor to the marked line 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 evening and morning measurements. Bring the recording to class.
Task 3.
Measure the thickness of the sheet of paper.
Take a book slightly over 1cm thick and, opening the top and bottom covers of the binding, place a ruler on the stack of paper. Pick up a stack with a thickness of 1 cm = 10 mm = 10,000 microns. By dividing 10,000 microns by the number of sheets, express the thickness of one sheet in microns. Write the result in a notebook. Think about how you can increase the measurement accuracy?
Task 4.
Determine the volume of a matchbox, rectangular las-teak, 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 cubic decimeters (liters) and write it down. Take measurements and calculate the volumes of the 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, observe its movement for one minute (on an electronic watch, observe the digital values). Next, ask someone to mark out loud the beginning and end of the minute by the hour, while you yourself close your eyes, and with your eyes closed, perceive the duration of one minute. Do the opposite: while standing with your eyes closed, try to set the duration to one minute. Have another person monitor you by the hour.
Task 6.
Learn how to quickly find your heart rate, then take a second or electronic watch and set how many heartbeats are observed in one minute. Then do the reverse work: counting the heartbeats, set the duration of one minute (entrust the watch to another person)
Note. The great scientist Galileo, observing the rocking of the chandelier in the Florentine Cathedral and using (instead of the clock) the beats of his own pulse, established the first law of oscillation of a pendulum, which formed the basis of the doctrine of oscillatory motion.
Task 7.
Using a stopwatch, set as precisely as possible the number of seconds in which you run the distance of 60 (100) m. Divide the distance by the time, i.e. determine the average speed in meters per second. Convert meters per second to kilometers per hour. Write the results in a notebook.
Pressure.
Exercise 1.
Determine the pressure generated by the stool. Place a piece of paper in a box under the chair leg, circle the leg with a sharpened pencil and, taking out the sheet, count the number of square centimeters. Calculate the footprint of the four chair legs. Think about how else you can calculate the area of support of the legs?
Find out your mass along with the chair. This can be done with a human scale. To do this, you need to pick up a chair and stand on the scales, i.e. weigh yourself along with the chair.
If you cannot find out the mass of the chair you have for some reason, take the mass of the chair equal to 7 kg (the average mass of chairs). Add the average stool weight to your own body weight.
Calculate your weight with the chair. To do this, the sum of the masses of the chair and the 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 on the chair without touching the floor with your feet. Write down all measurements and calculations in a notebook and bring them to class.
Task 2.
Pour water into the glass all the way to the rim. Cover the glass with a piece of thick paper and, holding the paper with your palm, quickly turn the glass upside down. Now remove your palm. The water will not pour 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 distortion of the piece of paper and with still insufficient experience, water can be poured at first.
Task 3.
"Diving bell" is a large metal cap, which is lowered to the bottom of the reservoir with its open side to carry out any work. After dropping it into water, the air contained in the hood is compressed and does not allow water to enter the device. Only a little water remains at the very bottom. In such a bell, people can move and do the work assigned to them. Let's make a model of this device.
Take a glass and plate. Pour water into a plate and place a glass turned upside down in it. The air in the glass will be compressed and the bottom of the plate under the glass will be very slightly flooded with water. Place a cork on the water before placing the glass on the plate. It will show how little water is left at the bottom.
Task 4.
This entertaining experience is about three hundred years old. He is attributed to the French scientist Rene Descartes (in Latin his surname is Cartesius). The experience was so popular that the "Cartesian diver" toy was created on its basis. You and I can do this experience. This will require a plastic bottle with a stopper, an eyedropper, and water. Fill the bottle with water, leaving two to three millimeters up to the edge of the neck. Take a pipette, put some water in it and dip 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 ensure that the pipette is submerged from a light push with a finger, and then it slowly floats up. Now close the cap 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 float up again. The fact is that we slightly squeezed the air in the neck of the bottle and this pressure was transferred to the water. Water entered the pipette - it became heavier and drowned. When the pressure was removed, the compressed air inside the pipette removed excess water, and our "diver" became lighter and floated up. If at the beginning of the experiment the "diver" does not obey you, then it is necessary 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 the increased pressure on the walls of the bottle enters the pipette, and when the pressure is released, it leaves it.
Task 5.
Make the fountain known in the history of physics as Heron's fountain. Insert a piece of drawn-out glass tube through the stopper in a thick-walled bottle. Pour as much water into the bottle as needed to keep the end of the tube submerged. Now, in two or three steps, blow air into the bottle with your mouth, squeezing the end of the tube after each blow. Release your finger and watch the fountain.
If you want a very strong fountain, then use a bicycle pump to pump air. However, remember that from 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 rupture the bottle, so you need to use the pump very carefully.
Archimedes' law.
Exercise 1.
Prepare a wooden stick (twig), a wide jar, a bucket of water, a wide bottle with a stopper, and a rubber string at least 25 cm long.
1. Push the stick into the water and watch as it is pushed out of the water. Do this several times.
2. Slide the can into the water upside down and watch as it is pushed out of the water. Do this several times. Remember how difficult it is to push the bucket upside down into a barrel of water (if you haven't observed this, do it at any opportunity).
3. Fill a bottle with water, close the stopper and tie a rubber string to it. Holding the thread by the free end, observe how it shortens as the bubble is immersed in water. Do this several times.
4. Tin plate sinks on water. Bend the edges of the plate so that you get a box. Place it on water. She swims. Instead of a tin plate, you can use a piece of foil, preferably hard. Make a foil box and place in water. If the box (made of foil or metal) does not leak, then it will float on the surface of the water. If the box picks up water and sinks, consider how to fold it so that no water gets inside.
Describe and explain these phenomena in your notebook.
Task 2.
Take a piece of boot wax or wax the size of an ordinary hazelnut, make a regular ball out of it, and using a small load (insert a piece of wire) make it sink smoothly in a glass or test tube of water. If the ball sinks without load, then, of course, it should not be loaded. In the absence of wax or wax, you can cut a small ball out of the flesh of a raw potato.
Add a little saturated solution of pure table salt to the water and stir gently. First ensure that the ball is balanced in the middle of the glass or test tube, and then so that it floats to the surface of the water.
Note. The proposed experiment is a variant of the well-known experiment with a hen's egg and has a number of advantages over the last experiment (it does not require a freshly laid hen's egg, a large tall vessel and a large amount of salt).
Task 3.
Take a rubber ball, 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.
Surface tension forces.
Exercise 1.
Prepare a glass plate for this experiment. Wash it well with soap and warm water. When it's dry, 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 the stearin from the candle onto it to form a flat, flat stearin plate about the size of the bottom of a glass.
Place stearin and glass plates side by side. Place a small drop of water on each of them from a pipette. On a stearic plate, a hemisphere with a diameter of about 3 millimeters will turn out, and a drop will spread on a glass plate. Now take a glass plate and tilt it. The drop has already spread, and now it will continue to flow. Water molecules are more likely to be 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 smoked 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 safety razor blade, although steel, can float on the surface of the water. You just need to take care that it is not wetted with water. To do this, you need to lightly grease it. Place the blade gently on the surface of the water. Place a needle across the blade and one button at each 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. One gets the impression that 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 lubricating it with a thin layer of fat. It should be put on 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 training.
Pay attention to how the needle is positioned 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. Use the tips of a match to pull them together. Please note: as soon as the distance between the plugs decreases to half a centimeter, this water gap between the plugs will contract by itself, and the plugs will quickly be attracted to each other. But not only traffic jams tend to each other. They are also well attracted to the edge of the dishes in which they float. To do this, you just need to bring them closer to it at a short distance.
Try to explain the phenomenon you saw.
Task 4.
Take two glasses. Fill one of them with water and place it higher. Place another empty glass below. Dip the end of a strip of clean cloth into a glass of water, and its other end into the lower 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 cloth 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 add vegetable oil to it. The oil is immediately located in the middle of the vessel, forming a beautiful, transparent, yellow ball. The conditions have been created for the ball as if it were in zero gravity.
To do the Plateau experiment in miniature, you need to take a very small transparent bubble. It should contain a little sunflower oil - about two tablespoons. The fact is that after the experiment, the oil will become completely unusable, and the products must be protected.
Pour some sunflower oil into the prepared bottle. Take a thimble as a dish. Put a few drops of water and the same amount of cologne in it. Stir the mixture, add it to the pipette and pour one drop into the oil. If the drop, becoming a ball, goes to the bottom, it means that the mixture is heavier than the oil, it must be lightened. To do this, add one or two drops of cologne to the thimble. Cologne is made of alcohol and is lighter than water and oil. If the ball from the new mixture starts not to fall, but, on the contrary, to rise, then the mixture has become lighter than oil and a drop of water must be added to it. So, alternating the addition of water and cologne in small, drop doses, you can achieve that the ball of water and cologne will "hang" in the oil at any level. The classic Plato experience in our case looks the other way around: oil and a mixture of alcohol and water have changed places.
Note. Experience can be asked at home and when studying the topic "Archimedes' Law".
Task 6.
How to change the surface tension of water? Pour clean water into two bowls. Take scissors and from a sheet of paper in a box, cut two narrow strips one cell wide. Take one strip and, holding it over one plate, cut off pieces from the strip one cell at a time, trying to do this 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 either each other or the edges of the plate.
Take a bar of soap, pointed at the end, and touch the pointed end to the surface of the water in the middle of the ring of paper. What are you watching? Why do pieces of paper start scattering?
Now take another strip, cut off several pieces of paper from it over another plate and, touching a sugar cube to the middle of the surface of the water inside the ring, keep it in water for a while. Pieces of paper will move closer to each other while gathering.
Answer the question: how has the surface tension of water changed from the addition of soap to it and from the addition of sugar?
Exercise 1.
Take a long, heavy book, tie it with a thin thread, and attach a 20cm rubber thread to the thread.
Place the book on the table and very slowly begin to pull on the end of the rubber string. Try to measure the length of the stretched rubber string as the book begins to slide.
Measure the length of the stretched book while moving the book 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 as the book moves evenly on the rollers.
Compare the three results obtained 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 the hexagon pencil on the book parallel to the spine. Slowly lift the top edge of the book until the pencil begins to slide downward. Tilt the book down a little and secure it in that position by placing something under it. Now the pencil, if you put it back on the book, will not move out. It is held in place by friction force - the force of friction at rest. But as soon as this force is weakened a little - and for this it is enough to click your finger on the book - and the pencil will crawl down until it falls on the table. (The same experiment can be done, for example, with a pencil case, matchbox, eraser, etc.)
Think about why the nail is easier to pull out of the board if you rotate it around the axis?
It takes some effort to move a thick book across the table with one finger. 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 weak push with the little finger.
Do experiments and make a comparison of the static friction force, the sliding friction force and the rolling friction force.
Task 3.
In this experience, two phenomena can be observed at once: inertia, experiments with which will be described further, and friction.
Take two eggs, one raw and one hard-boiled. Swirl both eggs on a large plate. You can see that a boiled egg behaves differently than a raw one: it rotates much faster.
In a boiled egg, the white and yolk are rigidly connected to their shell and to each other, since are in a solid state. And when we unwind a raw egg, then we first unwind only the shell, only then, due to friction, layer by layer, rotation is transferred to the egg white and yolk. Thus, the liquid white and yolk, by their friction between the layers, inhibit the rotation of the shell.
Note. Instead of raw and boiled eggs, you can twist two pots, in one of which there is water, and in the other there is the same amount of cereal.
The center of gravity.
Exercise 1.
Take two faceted pencils and hold them parallel in front of you with a ruler on top of them. Start bringing the pencils closer together. The convergence will occur in alternating movements: either one pencil moves, the other. Even if you want to interfere with their movement, you will fail. They will still move in turn.
As soon as the pressure on one pencil increases and the friction increases so much that the pencil cannot move 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 the increase in 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 be done with a stick, holding it on outstretched fingers. As you move your fingers, you will notice that they, too, moving alternately, will meet under the very middle of the stick. True, this is just a special case. Try this with a regular floor brush, 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. A pocket knife (folding) you probably have a pencil too. Sharpen the pencil so that it has a sharp end, and stick a half-open penknife just above the end. Place the tip of your pencil on your index finger. Find a position of the half-open knife on the pencil so that the pencil rests on your 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 a long, narrow edge and place a headless match on the box. This match will serve as a support for another match. Take a match with a head and balance it on the support so that it lies horizontally. Use a pen to mark the position of the center of gravity of the match with the head.
Scrape the head off the match and place the match on the support so that the ink dot you marked rests on the support. Now you will not succeed: 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 notice in which direction it has moved. Use a pen to mark the center of gravity of the headless match.
Bring the two-dot match to class.
Task 4.
Determine the position of the center of gravity of the flat figure.
Cut out a figure of an arbitrary (some fancy) shape from cardboard and poke several holes in different arbitrary places (it is better if they are located closer to the edges of the figure, this will increase the accuracy). Drive a small, unheaded stud or needle into a vertical wall or rack and hang the 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 the stud so that it points the vertical direction of the non-suspended figure. Mark the vertical direction of the thread on the shape with a pencil.
Remove the figure, hang it by any other hole, and again, using a plumb line and a pencil, mark the vertical direction of the thread on it.
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 kept almost horizontal. The more accurately the experiment is done, the more horizontal the figure will hold.
Task 5.
Determine the center of gravity of the hoop.
Take a small hoop (such as a hoop) or make a ring out of a flexible twig, a narrow strip of plywood, or stiff cardboard. Hang it on a nail and lower the plumb line from the hanging point. When the plumb line has calmed down, mark on the hoop the points where it touches the hoop and between these points pull and secure a piece of thin wire or fishing line (you need to pull tight enough, but not so much that the hoop changes its shape).
Hang the hoop on the stud at any other point and do the same. The point of intersection 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 body substance.
Tie a thread to the intersection of the wires or lines and hang the hoop on it. The hoop will be in indifferent equilibrium, since the center of gravity of the hoop and its point of 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 support area: the lower the center of gravity and the larger the support area, the more stable the body is.
Keeping this in mind, take a block or an empty matchbox and, placing it alternately on the paper in the box on the widest, on the middle and on the smallest edge, circle each time with karan-dash to get three different areas of support. Calculate the dimensions in square centimeters for each area and write them down on paper.
Measure and record the height of the box's center of gravity for all three cases (the matchbox's center of gravity lies at the intersection of the diagonals). Draw a conclusion at which position of the boxes is the most stable.
Task 7.
Sit in a chair. Stand with your feet upright, without slipping them under the seat. Sit perfectly straight. Try to stand without bending forward, without stretching your arms forward, or moving your legs under the seat. You will not succeed - you will not be able to get up. Your center of gravity, which is somewhere in the middle of your body, will prevent you from standing up.
What condition must be met in order to get up? You need to bend 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 your feet or between them. Then the balance of your body will be stable enough, you can easily stand up.
Well, now try to stand up with dumbbells or an iron in your hands. Stretch your arms forward. You may be able to stand up without bending over or bending your legs under you.
Exercise 1.
Place a postcard on the glass, and place a coin or checker on the card so that the coin is above the glass. Click on the postcard. 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 25cm high on one half of the sheet.
Slightly lifting the second half of the sheet above the table level 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 very slowly now. The books will move 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 does not hold up, take two threads. Slowly lift the hammer up by the thread. The hammer will hang on a string. 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 does not break anything under it when falling). 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 quickly across the table 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) very quickly pull the chute and stop it abruptly;
b) pull the chute slowly and stop abruptly.
Task 5.
Cut the apple in half, but not all the way to the end, and leave it hanging 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 happens when the wood is chopped: if it was not possible to split the block, it is usually turned over and, with all the strength, they hit the butt of the ax on a solid support. The block, continuing to move by inertia, sits deeper on the ax and splits in two.
Exercise 1.
Place a wooden board and a mirror on the table next to it. 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, at the blackboard and at the mirror.
Touch the mirror with your palm. You will feel the coldness of the glass. Touch the board immediately. It will seem much warmer. What's the matter? After all, the temperature of the air, boards and mirrors are the same.
Why did glass seem colder than wood? Try to answer this question.
Glass is a good heat conductor. As a good conductor of heat, glass will immediately begin to heat up from your hand, greedily "pumping out" the heat from it. This makes you feel cold in the palm of your hand. Wood conducts heat worse. It will also begin to "pump" heat into itself, heating up by hand, but it does it much more slowly, so you do not feel a sharp cold. Wood seems to be warmer than glass, although both have the same temperature.
Note. You can use polystyrene 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 its walls gradually fog up. This experience confirms the properties of the vapors to diffuse through the baffles.
Task 3.
Take a glass bottle and cool it well (for example, put it out in the cold or 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 the progress report to class.
Task 4.
Take a glass bottle, warm it well over water vapor and pour boiling water into it to the very top. Place the bottle on the windowsill and mark the time. After 1 hour, mark the new water level in the bottle.
Bring the progress report to class.
Task 5.
Establish the dependence of the rate of evaporation on the area of the free surface of the liquid.
Fill a test tube (small bottle or vial) with water and pour onto a tray or flat plate. Refill the same container with water and place it next to the plate in a quiet place (for example, on a cabinet), letting the water evaporate calmly. Record the start date of the experiment.
When the water on the plate has evaporated, mark and record the time again. See how much of the water has evaporated from the test tube (bottle).
Make a conclusion.
Task 6.
Take a tea glass, fill it with chunks of pure ice (for example, from a chopped icicle) and bring the glass into the room. Pour into a glass to the brim with room water. When all the ice has melted, watch how the water level in the glass has changed. Draw 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 sublimate. Take half a glass of dry snow on a frosty day in winter and put it outside the house under some kind of awning so that no snow from the air gets into the glass.
Record the start date of the experiment and observe the sublimation of the snow. When all the snow is gone, write down the date again.
Write a report.
Topic: "Determination of the average speed of a person's movement."
Purpose: using the speed formula, determine the speed of a person's movement.
Equipment: mobile phone, ruler.
Progress:
1. Determine the length of your stride with a ruler.
2. Walk through the entire apartment, counting the number of steps.
3. Using the stopwatch of your mobile phone, determine the time of your movement.
4. Using the speed formula, determine the speed of movement (all values must be expressed in SI).
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 carton using a checkweigher in the store (there must be a label on the bag).
2. Determine the size of the package with a ruler: 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 tabular density value.
5. Make a conclusion about the results of the work.
Topic: "Determination of the weight of a carton of milk."
Purpose: Using the value of the tabular density of the substance, calculate the weight of the milk carton.
Equipment: milk carton, substance density table, ruler.
Progress:
1. Determine the size of the package with a ruler: length, width, height, - convert the measurement data to the SI system and calculate the volume of the package.
2. Using the value of the tabular density of milk, determine the weight of the bag.
3. Using the formula, determine the weight of the package.
4. Draw graphically the linear dimensions of the package and its weight (two drawings).
5. Make a conclusion about the results of the work.
Topic: "Determination of the pressure exerted by a person on the floor"
Purpose: using a formula, determine the pressure of a person on the floor.
Equipment: bathroom scales, checkered notebook sheet.
Progress:
1. Stand on a notebook sheet and circle your foot.
2. To determine the area of your foot, count the number of complete cells and separately - incomplete cells. Reduce the number of incomplete cells by half, add the number of full cells to the result obtained, divide the sum by four. This is the area of one foot.
3. Using a bathroom scale, determine your body weight.
4. Using the pressure formula for a rigid body, determine the pressure applied to the floor (all values must be expressed in SI units). Don't forget that the person is standing 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: "Verification of the phenomenon of hydrostatic paradox."
Purpose: Using the general pressure formula, determine the pressure of the liquid at the bottom of the vessel.
Equipment: measuring vessel, glass with high sides, vase, ruler.
Progress:
1. Determine the height of the liquid poured into the glass and vase with a ruler; it should be the same.
2. Determine the mass of liquid in the glass and 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 bottom diameter with a ruler and use the formula for the area of a circle.
4. Using the general pressure formula, determine the water pressure at the bottom in the glass and vase (all values must be expressed in SI units).
5. Illustrate the course of the experiment with a picture.
Topic: "Determination of the density of the human body."
Purpose: using Archimedes' law and the density calculation formula, determine the density of the human body.
Equipment: liter jar, floor scales.
Progress:
4. Using your bathroom scale, determine your weight.
5. Use the formula to determine the density of your body.
6. Make a conclusion about the results of the work.
Topic: "Definition of Archimedean force."
Purpose: using Archimedes' law, to determine the buoyancy force acting from the side of the liquid on the human body.
Equipment: liter jar, bath.
Progress:
1. Fill the bathtub with water, mark the water level along the edge.
2. Immerse yourself in the bath. This will increase the liquid level. Mark around the edge.
3. Using a liter jar, determine your volume: it is equal to the difference between the volumes marked on the edge of the bath. Convert the obtained result to the SI system.
5. Illustrate the experiment performed by indicating the Archimedes force vector.
6. Make a conclusion based on the results of the work.
Topic: "Determination of the swimming conditions of the body."
Objective: Using Archimedes' Law, locate your body in a fluid.
Equipment: liter jar, floor scales, bathtub.
Progress:
1. Fill the bathtub with water, mark the water level along the edge.
2. Immerse yourself in the bath. This will increase the liquid level. Mark around the edge.
3. Using a liter jar, determine your volume: it is equal to the difference between the volumes marked on the edge of the bath. Convert the obtained result to the SI system.
4. Using Archimedes' law, determine the buoyancy of the liquid.
5. Use a bathroom scale to measure your weight and calculate your weight.
6. Compare your weight with the magnitude of the Archimedean force and locate your body in the liquid.
7. Illustrate the experiment performed by indicating the vectors of weight and force of Archimedes.
8. Make a conclusion on the results of the work.
Topic: "Definition of work to overcome the force of gravity."
Purpose: using the formula of work, determine the physical activity of a person when making a jump.
Progress:
1. Determine the height of your jump with a ruler.
3. Using the formula, determine the work required to complete the jump (all values must be expressed in SI).
Topic: "Determination of the landing speed."
Purpose: using the formulas of kinetic and potential energy, the law of conservation of energy, determine the speed of landing when making a jump.
Equipment: bathroom scales, ruler.
Progress:
1. Determine the height of the chair from which the jump will be made with a ruler.
2. Determine your weight using the floor scale.
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 values must be expressed in SI).
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 a boat in the form of a triangular arrow from cardboard.
2. Pour water into a bowl.
3. Place the boat carefully on the surface of the water.
4. Dip your finger in dishwashing liquid.
5. Carefully immerse your finger in the water just behind the boat.
6. Describe the observations.
7. Make a conclusion.
Topic: "How various fabrics absorb moisture"
Equipment: different scraps of cloth, water, tablespoon, glass, rubber band, scissors.
Progress:
1. Cut a 10x10 cm square from various pieces of fabric.
2. Cover the glass with these pieces.
3. Secure them to the glass with a rubber band.
4. Carefully pour a spoonful of water over each piece.
5. Remove the flaps, pay attention to the amount of water in the glass.
6. Draw conclusions.
Topic: "Mixing immiscible"
Equipment: plastic bottle or transparent disposable glass, vegetable oil, water, spoon, dishwashing liquid.
Progress:
1. Pour some oil and water into a glass or bottle.
2. Mix oil and water thoroughly.
3. Add some dishwashing liquid. Stir.
4. Describe the observations.
Topic: "Determining the distance traveled from home to school"
Progress:
1. Select a route.
2. Calculate the approximate length of one step using a tape measure or a measuring tape. (S1)
3. Calculate the number of steps when driving along the selected route (n).
4. Calculate the length of the path: S = S1 · n, in meters, kilometers, fill in the table.
5. Draw to scale the route of movement.
6. Make a conclusion.
Topic: "Interaction of bodies"
Equipment: glass, cardboard.
Progress:
1. Place the glass on the cardboard.
2. Pull the cardboard slowly.
3. Quickly pull out the cardboard.
4. Describe the movement of the order book in both cases.
5. Make a conclusion.
Topic: "Calculating the density of a bar of soap"
Equipment: a bar of laundry soap, a ruler.
Progress:
3.Use a ruler to 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 the bar of soap: p = m / V
6. Fill in the table:
7. Convert the density, expressed in g / cm 3, in kg / m 3
8. Make a conclusion.
Topic: "Was the air heavy?"
Equipment: two identical balloons, a wire hanger, two clothespins, a safety pin, a thread.
Progress:
1. Inflate two balloons to a single size and tie with a thread.
2. Hang the hanger on the handrail. (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 bead 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 a 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 density of air, calculate the mass of air in the room: m = p · V.
4. Calculate the weight of the air: P = mg.
5. Fill in the table:
6. Make a conclusion.
Topic: "Feel the friction"
Equipment: dishwashing liquid.
Progress:
1. Wash your hands and dry them.
2. Quickly rub your palms together for 1-2 minutes.
3. Apply some dishwashing liquid to the palms of your hands. Rub your palms again for 1-2 minutes.
4. Describe the observed phenomena.
5. Make a conclusion.
Topic: "Determination of the dependence of gas pressure on temperature"
Equipment: balloon, thread.
Progress:
1. Inflate the balloon, tie it with a thread.
2. Hang the ball on the street.
3. After a while, pay attention to the shape of the ball.
4. Explain why:
a) By directing the stream of air when the balloon is inflated in one direction, we make it swell in all directions at once.
b) Why not all balls take a spherical shape.
c) Why, when the temperature drops, the ball changes its shape.
5. Make a conclusion.
Topic: "Calculation of the force with which the atmosphere presses on the surface of the table?"
Equipment: tape measure.
Progress:
1. Using a tape measure or a measuring tape, calculate the length and width of the table, express in meters.
2. Calculate the table area: S = a · b
3. Take the pressure from the atmosphere equal to Рat = 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: "Is it floating or sinking?"
Equipment: large bowl, water, paper clip, apple slice, pencil, coin, cork, potato, salt, glass.
Progress:
1. Pour water into a bowl or basin.
2. Submerge all of the items listed carefully in the water.
3. Take a glass of water, dissolve 2 tablespoons of salt in it.
4. Dip into the solution those objects that were drowned in the first.
5. Describe the observations.
6. Make a conclusion.
Topic: "Calculation of the work done by a student when going up from the first to the second floor of a school or home"
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 = Sо · n.
4. If possible, determine your body weight, if not, take approximate data: m, kg.
5. Calculate the force of gravity of your body: F = mg
6. Determine the work: A = F · S.
7. Fill in the table:
8. Make a conclusion.
Topic: "Determining the power that a student develops by evenly rising slowly and quickly from the first to the second floor of a school or home"
Equipment: work data "Calculation of the work done by the student when climbing from the first to the second floor of a school or home", a stopwatch.
Progress:
1. Using the data of the work "Calculation of the work done by the student when going up from the first to the second floor of a school or at home" to determine the work done when going up the stairs: A.
2. Using a stopwatch, determine the time taken to slowly climb the stairs: t1.
3. Using the 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 the table:
6. Make a conclusion.
Topic: "Clarification of the condition of the balance of the lever"
Equipment: ruler, pencil, eraser, old coins (1 k, 2 k, 3 k, 5 k).
Progress:
1. Place a pencil under the center of the ruler to keep the ruler in balance.
2. Place an elastic band on one end of the ruler.
3. Balance the lever with coins.
4. Considering that the mass of old coins 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 end of the ruler.
6. Measure the shoulders l1 and l2, m.
7. Balance the lever with m2 kg coins.
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. Complete the table.
11. Make a conclusion.
Bibliographic reference
Vikhareva E.V. HOME EXPERIENCES IN PHYSICS 7-9 CLASSES // Start in science. - 2017. - No. 4-1. - S. 163-175;URL: http://science-start.ru/ru/article/view?id=702 (date of access: 25.12.2019).
Ministry of Education and Science of the Chelyabinsk Region
Plastovskiy technological branch
GBPOU SPO "Kopeysk Polytechnic College named after S.V Khokhryakova "
MASTER CLASS
"EXPERIENCES AND EXPERIMENTS
FOR KIDS"
Educational - research work
"Entertaining physical experiences
from scrap materials "
Leader: Yu.V. Timofeeva, physics teacher
Performers: students of the OPI group - 15
annotation
Physical experiments increase interest in the study of physics, develop thinking, teach to apply theoretical knowledge to explain various physical phenomena occurring in the surrounding world.
Unfortunately, due to the congestion of the educational material in physics lessons, insufficient attention is paid to entertaining experiments.
With the help of experiments, observations and measurements, the relationship between various physical quantities can be investigated.
All the phenomena observed during entertaining experiments have a scientific explanation, for this they used the fundamental laws of physics and the properties of the matter around us.
TABLE OF CONTENTS
| Introduction | ||
| Main content | ||
| Organization of research work | ||
| Methodology for conducting various experiments | ||
| Research results | ||
| Conclusion | ||
| List of used literature | ||
| Applications |
INTRODUCTION
Without a doubt, all our knowledge begins with experience.
(Kant Emmanuel - German philosopher 1724-1804)
Physics is not only scientific books and complex laws, not only huge laboratories. Physics is also interesting experiments and entertaining experiments. Physics are magic tricks shown in a circle of friends, funny stories and funny homemade toys.
Most importantly, any material at hand can be used for physical experiments.
Physical experiments can be done with balls, glasses, syringes, pencils, straws, coins, needles, etc.
Experiments increase interest in the study of physics, develop thinking, teach to apply theoretical knowledge to explain various physical phenomena occurring in the surrounding world.
When conducting experiments, it is necessary not only to draw up a plan for its implementation, but also to determine the methods for obtaining some data, independently assemble installations and even design the necessary instruments for reproducing this or that phenomenon.
But, unfortunately, due to the overload of the educational material in physics lessons, insufficient attention is paid to entertaining experiments, much attention is paid to theory and problem solving.
Therefore, it was decided to conduct research work on the topic "Entertaining experiments in physics from scrap materials."
The objectives of the research work are as follows:
To master the methods of physical research, to master the skills of correct observation and the technique of physical experiment.
Organization of independent work with various literature and other sources of information, collection, analysis and generalization of material on the topic of research work.
Teach students, apply scientific knowledge to explain physical phenomena.
To instill in students a love of physics, to strengthen their concentration on understanding the laws of nature, and not on their mechanical memorization.
When choosing a research topic, we proceeded from the following principles:
Subjectivity - the chosen topic is in our interests.
Objectivity - the topic we have chosen is relevant and important in scientific and practical terms.
Ability - the tasks and goals we set in our work are real and achievable.
1. MAIN CONTENT.
The research work was carried out according to the following scheme:
Formulation of the problem.
Study of information from various sources on this issue.
The choice of research methods and their practical mastery.
Collecting your own material - collecting materials at hand, conducting experiments.
Analysis and generalization.
Formulation of conclusions.
During the research work, the following physical research methods were used:
1. Physical experience
The experiment consisted of the following stages:
Clarification of the conditions of the experiment.
This stage provides for acquaintance with the conditions of the experiment, determination of the list of necessary tools and materials at hand, and safe conditions during the experiment.
Drawing up a sequence of actions.
At this stage, the procedure for conducting the experiment was outlined, if necessary, new materials were added.
Conducting the experiment.
2. Observation
When observing the phenomena occurring in the experiment, we paid special attention to the change in physical characteristics, while we were able to detect regular connections between various physical quantities.
3. Simulation.
Simulation is the foundation of any physical research. During the experiments, we simulated various situational experiments.
In total, we have modeled, conducted and scientifically explained several entertaining physical experiments.
2. Organization of research work:
2.1 Technique for conducting various experiments:
Experience No. 1 Candle by bottle
Devices and materials: candle, bottle, matches
Stages of the experiment
Put a lighted candle behind the bottle, and stand yourself so that your face is 20-30 cm from the bottle.
It is worth blowing now, and the candle will go out, as if there is no barrier between you and the candle.
Experience number 2 Swirling snake
Appliances and materials: thick paper, candle, scissors.
Stages of the experiment
Cut a spiral out of thick paper, stretch it slightly and place it on the end of the curved wire.
By holding this spiral above the candle in an upward flow of air, the snake will rotate.
Devices and materials: 15 matches.
Stages of the experiment
Put one match on the table, and 14 matches across it so that their heads stick out upward, and the ends touch the table.
How to pick up the first match, holding it by one end, and with it all the other matches?
Experience number 4 Paraffin motor
Devices and materials:candle, knitting needle, 2 glasses, 2 plates, matches.
Stages of the experiment
We don't need electricity or gas to make this motor. For this we only need ... a candle.
Heat a knitting needle and stick it with their heads into the candle. This will be the axis of our engine.
Place the candle with a knitting needle on the edges of two glasses and balance.
Light a candle at both ends.
Experiment # 5 Thick air
We live by the air we breathe. If this doesn't seem magical enough to you, do this experiment to find out what other magic the air is capable of.
Props
Protective glasses
Pine plank 0.3x2.5x60 cm (can be purchased at any lumber store)
Newspaper sheet
Ruler
Preparation
Let's start the scientific magic!
Wear safety glasses. Announce to the audience: “There are two kinds of air in the world. One of them is skinny and the other is fat. Now I will do magic with the help of greasy air. "
Place the plank on the table so that about 6 inches (15 cm) protrudes over the edge of the table.
Say: "Thick air, sit on the board." Hit the end of the board that protrudes over the edge of the table. The board will jump into the air.
Tell the audience that it must be skinny air. Put the plank back on the table as in step 2.
Place a piece of newsprint on the board as shown in the figure, with the board in the middle of the sheet. Smooth the newspaper so that there is no air between it and the table.
Say again, "Thick air, sit on the board."
Hit the protruding end with the edge of your palm.
Experience No. 6 Waterproof paper
Props
Paper towel
Cup
A plastic bowl or bucket that can hold enough water to completely cover the glass
Preparation
Lay out everything you need on the table
Let's start the scientific magic!
Announce to the audience: "With the help of my magical skill, I can make the piece of paper dry."
Crumple up a paper towel and place it on the bottom of your glass.
Turn the glass over and make sure the wad of paper stays in place.
Say some magic words over the glass, for example: "magical powers, protect the paper from water." Then slowly lower the inverted glass into a bowl of water. Try to keep the glass as level as possible until it is completely hidden under water.
Take the glass out of the water and shake off the water. Turn the glass upside down and take out the paper. Let the audience feel it and make sure it stays dry.
Experience number 7 Flying ball
Have you seen a man rise into the air at a magician's performance? Try a similar experiment.
Please note: This experiment will require a hairdryer and adult help.
Props
Hairdryer (must be used only by an adult helper)
2 thick books or other heavy objects
Ping pong ball
Ruler
Adult assistant
Preparation
Place the hairdryer on the table with the hot air blowing hole up.
Use books to set it in this position. Make sure they don't cover the opening on the side where air is drawn into the hair dryer.
Plug in the hair dryer.
Let's start the scientific magic!
Ask an adult audience member to be your assistant.
Announce to the audience: "Now I will make an ordinary ping-pong ball fly through the air."
Take the ball in your hand and let it go so that it falls on the table. Tell the audience: “Oops! I forgot to say the magic words! "
Say the magic words over the ball. Have your assistant turn on the hair dryer at full power.
Gently place the balloon over a hairdryer in a stream of air, about 45 cm from the blow hole.
Tips for a learned wizard
Depending on the force of blowing, you may need to place the balloon slightly higher or lower than indicated.
What else can be done
Try to do the same with balls of different sizes and weights. Will the experience be equally good?
2.2 RESULTS OF THE STUDY:
1) Experience No. 1 Candle by bottle
Explanation:
The candle will float little by little, and the water-cooled paraffin at the edge of the candle will melt more slowly than the paraffin surrounding the wick. Therefore, a rather deep funnel forms around the wick. This emptiness, in turn, lightens the candle, which is why our candle will burn out to the end..
2) Experience number 2 Swirling snake
Explanation:
The snake rotates because there is an expansion of air under the influence of heat and the transformation of warm energy into movement.
3) Experience number 3 Fifteen matches on one
Explanation:
In order to raise all the matches, you only need to put another, fifteenth match on top of all the matches, in the hollow between them.
4) Experiment No. 4 Paraffin motor
Explanation:
A drop of paraffin will fall into one of the plates placed under the ends of the candle. The balance will be violated, the other end of the candle will pull and drop; at the same time, a few drops of paraffin will drain from it, and it will become lighter than the first end; it rises to the top, the first end will go down, drop a drop, become lighter, and our motor will start to work with might and main; gradually, the fluctuations of the candle will increase more and more.
5) Experience number 5 Thick air
When you hit the board for the first time, it bounces. But if you hit the board with the newspaper on it, the board breaks.
Explanation:
When you smooth out a newspaper, you remove almost all the air from under it. At the same time, a large amount of air on top of the newspaper presses on it with great force. When you hit the board, it breaks because the air pressure on the newspaper prevents the board from rising up in response to the force you put on.
6) Experience number 6 Waterproof paper
Explanation:
Air takes up a certain volume. There is air in the glass, no matter what position it is in. When you turn the glass upside down and slowly lower it into the water, the air remains in the glass. Water cannot enter the glass due to air. The air pressure turns out to be greater than the pressure of water tending to penetrate into the glass. The towel at the bottom of the glass remains dry. If the glass is turned on its side under water, air in the form of bubbles will come out of it. Then he can get into the glass.
8) Experience number 7 Flying ball
Explanation:
In fact, this trick does not contradict the force of gravity. It demonstrates an important ability of air called the Bernoulli principle. Bernoulli's principle is a law of nature, according to which any pressure of any fluid substance, including air, decreases with increasing speed of its movement. In other words, at a low air flow rate, it has a high pressure.
The air coming out of the hair dryer moves very quickly and therefore its pressure is low. The ball is surrounded on all sides by an area of low pressure, which forms a cone at the hole of the hair dryer. The air around this cone has a higher pressure, and does not allow the ball to fall out of the low pressure zone. The force of gravity pulls it down, and the force of the air pulls it up. Thanks to the combined action of these forces, the ball hangs in the air above the hair dryer.
CONCLUSION
Analyzing the results of entertaining experiments, we were convinced that the knowledge gained in physics lessons is quite applicable to solving practical issues.
With the help of experiments, observations and measurements, the dependences between various physical quantities were investigated.
All the phenomena observed during entertaining experiments have a scientific explanation, for this we used the fundamental laws of physics and the properties of the matter around us.
The laws of physics are based on empirically established facts. Moreover, the interpretation of the same facts often changes in the course of the historical development of physics. Facts accumulate through observation. But at the same time, one cannot be limited only to them. This is only the first step towards knowledge. Next comes the experiment, the development of concepts that allow for qualitative characteristics. In order to draw general conclusions from observations, to find out the causes of the phenomena, it is necessary to establish quantitative relationships between the quantities. If such a dependence is obtained, then a physical law is found. If a physical law is found, then there is no need to set an experiment in each individual case, it is enough to perform the appropriate calculations. Having studied experimentally the quantitative relationships between quantities, it is possible to identify patterns. On the basis of these regularities, a general theory of phenomena is being developed.
Therefore, there can be no rational teaching of physics without experiment. The study of physics and other technical disciplines involves the widespread use of the experiment, discussion of the features of its formulation and the observed results.
In accordance with the task set, all experiments were carried out using only cheap, small-sized materials at hand.
Based on the results of educational and research work, the following conclusions can be drawn:
In various sources of information, you can find and come up with many entertaining physical experiments performed with the help of improvised equipment.
Entertaining experiments and home-made physical devices increase the range of demonstrations of physical phenomena.
Entertaining experiments allow you to test the laws of physics and theoretical hypotheses.
BIBLIOGRAPHY
M. Di Spezio "Entertaining experiences", LLC "Astrel", 2004.
F.V. Rabiza "Funny Physics", Moscow, 2000.
L. Halperstein "Hello, Physics", Moscow, 1967.
A. Tomilin "I want to know everything", Moscow, 1981.
M.I. Bludov "Conversations on Physics", Moscow, 1974.
ME AND. Perelman "Entertaining tasks and experiments", Moscow, 1972.
ANNEXES
Disk:
1. Presentation "Entertaining physical experiments from scrap materials"
2. Video "Entertaining physical experiments from scrap materials"
In school physics lessons, teachers always say that physical phenomena are everywhere in our lives. Only we often forget about it. Meanwhile, the amazing is near! Do not think that you need something supernatural to organize physical experiences at home. And here is some evidence for you;)
Magnetic pencil
What needs to be prepared?
- The battery.
- Thick pencil.
- Insulated copper wire 0.2–0.3 mm in diameter and several meters long (the more the better).
- Scotch.
Experiment
Wrap the wire close to the loop on the pencil, not reaching its edges by 1 cm. One row is over - wind the other on top in the opposite direction. And so, until all the wire runs out. Do not forget to leave the two ends of the wire 8-10 cm free. To prevent the coils from unwinding after winding, secure them with tape. Strip the loose ends of the wire and connect them to the battery contacts.
What happened?
It turned out to be a magnet! Try to bring small iron objects to it - a paper clip, a hairpin. Are attracted!
Lord of water
What needs to be prepared?
- A plexiglass stick (for example, a student's ruler or an ordinary plastic comb).
- Dry cloth made of silk or wool (for example, woolen sweater).
Experiment
Open the tap for a thin stream of water to flow. Rub your wand or hairbrush firmly on the prepared cloth. Move the stick quickly to the stream of water without touching it.
What's going to happen?
The stream of water will bend in an arc, being attracted to the stick. Try the same thing with two sticks and see what happens.
Spinning top
What needs to be prepared?
- Paper, needle and eraser.
- A stick and dry woolen cloth from previous experience.
Experiment
You can control not only water! Cut a strip of paper 1–2 cm wide and 10–15 cm long, and bend around the edges and in the middle as shown. Stick the sharp end of the needle into the eraser. Balance the top on the needle. Prepare the "magic wand", rub it on a dry cloth and bring it to one of the ends of the paper strip from the side or top, without touching it.
What's going to happen?
The strip will swing up and down like a swing, or it will spin like a carousel. And if you can cut a butterfly out of thin paper, then the experience will be even more interesting.
Ice and flames
(the experiment is carried out on a sunny day)
What needs to be prepared?
- A small round bottom cup.
- A piece of dry paper.
Experiment
Pour water into a cup and place in the freezer. When the water turns to ice, remove the cup and place it in a container of hot water. After a while, the ice will separate from the cup. Now go out to the balcony, put a piece of paper on the stone floor of the balcony. Use a piece of ice to focus the sun on the piece of paper.
What's going to happen?
The paper should be charred, because there is more than just ice in your hands ... You guessed that you made a magnifying glass?
Wrong mirror
What needs to be prepared?
- A transparent jar with a tight-fitting lid.
- Mirror.
Experiment
Pour an excess of water into the jar and close the lid to prevent air bubbles from getting inside. Place the jar upside down to the mirror. Now you can look in the "mirror".
Zoom in on your face and look inside. There will be a thumbnail image. Now start tilting the can to the side without taking it away from the mirror.
What's going to happen?
The reflection of your head in the can, of course, will also tilt until it is turned upside down, while the legs will not be visible. Pick up the can and the reflection flips over again.
Bubble cocktail
What needs to be prepared?
- A glass with a strong solution of sodium chloride.
- Flashlight battery.
- Two pieces of copper wire approximately 10 cm long.
- Fine sandpaper.
Experiment
Sand the ends of the wire with a fine emery cloth. Connect one end of the wires to each pole of the battery. Dip the free ends of the wires into a glass with a solution.
What happened?
Bubbles will rise near the lowered ends of the wire.
Lemon battery
What needs to be prepared?
- Lemon, thoroughly washed and wiped dry.
- Two pieces of insulated copper wire, approximately 0.2–0.5 mm thick and 10 cm long.
- A steel paper clip.
- A light bulb from a pocket flashlight.
Experiment
Strip the opposite ends of both wires at a distance of 2-3 cm. Insert a paper clip into the lemon, screw the end of one of the wires to it. Stick the end of the second wire into the lemon 1–1.5 cm from the paper clip. To do this, first pierce the lemon in this place with a needle. Take the two free ends of the wires and attach the light bulb to the contacts.
What's going to happen?
The light will come on!
Experiment is one of the most informative ways of knowing. Thanks to him, it is possible to obtain various and extensive titles about the studied phenomenon or system. It is the experiment that plays a fundamental role in physical research. Beautiful physical experiments remain in the memory of subsequent generations for a long time, and also contribute to the popularization of physical ideas among the masses. Here are the most interesting physical experiments according to the physicists themselves from a survey by Robert Crease and Stony Buck.
1. Experiment of Eratosthenes of Cyrene
This experiment is rightfully considered one of the most ancient to date. In the third century BC. Librarian of the Library of Alexandria, Erastofen Kirensky, measured the radius of the Earth in an interesting way. on the summer solstice in Siena, the sun was at its zenith, with the result that no shadows were observed from objects. At 5000 stadia north in Alexandria, at the same time, the Sun deviated from its zenith by 7 degrees. From here the librarian received information that the circumference of the Earth is 40 thousand km, and its radius is 6300 km. Erastofen received indicators only 5% less than today, which is simply amazing for the ancient measuring instruments he used.
2. Galileo Galilei and his very first experiment
In the 17th century, Aristotle's theory was dominant and unquestioning. According to this theory, the speed of a body falling directly depended on its weight. An example was a feather and a stone. The theory was flawed as it did not take air resistance into account.
Galileo Galilei doubted this theory and decided to conduct a series of experiments personally. He took a large cannonball and fired it from the Leaning Tower of Pisa, paired with a light musket bullet. Given their close streamlined shape, it was easy to neglect the air resistance and of course both objects landed at the same time, refuting Aristotle's theory. believes that you need to personally go to Pisa and throw something similar in appearance and different in weight from the tower in order to feel like a great scientist.
3. Galileo Galilei's second experiment
The second statement of Aristotle was that bodies under the action of force move at a constant speed. Galileo launched metal balls along an inclined plane and recorded the distance covered by them in a certain time. Then he doubled the time, but the balls traveled 4 times the distance during this time. Thus, the relationship was not linear, that is, the speed was not constant. From this, Galileo concluded that there was accelerated motion under the action of force.
These two experiments served as the basis for the creation of classical mechanics.
4. Henry Cavendish's experiment
Newton is the owner of the formulation of the law of universal gravitation, in which there is a gravitational constant. Naturally, the problem arose of finding its numerical value. But for this it would be necessary to measure the force of interaction between bodies. But the problem is that the gravitational force is rather weak, it would be necessary to use either gigantic masses or small distances.
John Michell was given the chance to come up with, and Cavendish to conduct in 1798 a rather interesting experiment. A torsion balance was used as a measuring device. Balls on thin ropes were attached to them on a rocker. Mirrors were attached to the balls. Then very large and heavy ones were brought to the small balls and the displacement was recorded according to the light beams. The result of a series of experiments was the determination of the value of the gravitational constant and the mass of the Earth.
5. The experiment of Jean Bernard Léon Foucault
Thanks to the huge (67 m) pendulum, which was installed in the Parisian Pantheon, Foucault in 1851, by the method of experiment, brought the fact of the Earth's rotation around its axis. The plane of rotation of the pendulum remains unchanged in relation to the stars, but the observer rotates with the planet. Thus, you can see how the plane of rotation of the pendulum is gradually shifting to the side. This is a fairly simple and safe experiment, unlike the one we wrote about in the article.
6. Isaac Newton's experiment
And again Aristotle's statement was tested. It was believed that different colors are mixtures in different proportions of light and darkness. The more darkness, the closer the color is to purple and vice versa.
People have long noticed that large monocrystals decompose light into colors. A series of experiments with prisms was carried out by the Czech naturalist Marcia English Chariot. Newton began a new series in 1672.
Newton set up physics experiments in a dark room, passing a thin beam of light through a small hole in the blackout curtains. This beam hit a prism and expanded into the colors of the rainbow on the screen. The phenomenon was called dispersion and was later theoretically substantiated.
But Newton went further, because he was interested in the nature of light and colors. He passed the rays through two prisms in succession. Based on these experiments, Newton concluded that color is not a combination of light and darkness, much less an attribute of an object. White light consists of all the colors that can be seen in dispersion.
7. Thomas Young's experiment
Until the 19th century, the corpuscular theory of light prevailed. It was believed that light, like matter, consists of particles. Thomas Jung, an English physicist and physicist, conducted an experiment in 1801 to test this claim. If we assume that light has a wave theory, then the same interacting waves should be observed as when throwing two stones into the water.
To simulate stones, Jung used an opaque screen with two holes and light sources behind it. Light passed through the holes and a pattern of light and dark stripes was formed on the screen. Light stripes formed where the waves reinforced each other, and dark ones where they extinguished.
8. Klaus Jonsson and his experiment
In 1961, the German physicist Klaus Jonsson proved that elementary particles have a particle-wave nature. For this, he conducted an experiment similar to Young's experiment, only replacing the rays of light with beams of electrons. As a result, we still managed to get an interference pattern.
9. Experiment by Robert Millikan
At the beginning of the nineteenth century, the idea arose of the presence of an electric charge in each body, which is discrete and determined by indivisible elementary charges. By that time, the concept of an electron was introduced as a carrier of this very charge, but it was not possible to experimentally detect this particle and calculate its charge.
The American physicist Robert Millikan succeeded in developing the perfect example of finesse in experimental physics. He isolated the charged water droplets between the condenser plates. Then, using X-rays, he ionized the air between the same plates and changed the charge of the droplets.
Loading...