The force of friction is an interesting experiment. Calculation of the average value of the friction force on the laminate

ROLLING AND SLIDING

Place the book on an angle and put a pencil on it. Will it slide or won't it slide?
It depends how you put it. If you put it along the slope, the pencil will not slip even with a large slope. What if across?
Oh, how it rolled! Especially if it is round, not hexagonal.

You can say: think, me too scientific experience! What is interesting in it?
And the interesting thing about this experiment is that when the pencil rolls, the friction is much less than when it crawls. Rolling is easier than dragging. Or, as physicists say, rolling friction is less than sliding friction.

That is why people invented wheels. In ancient times, wheels were not known, and even in summer, goods were carried on sledges. On the wall of one ancient temple a picture carved in Egypt: a huge stone statue carried across the land on a sleigh.

Rollers, and then wheels, appeared already several thousand years ago, sliding friction was replaced by more beneficial rolling friction.

Modern technology has made the following important step: bearings appeared, which are sliding, ball and roller.

To move a thick book on the table with one finger, you need to make some effort.

And if you put two round pencils under the book, which will be in this case roller bearings, the book will move easily with a slight push with the little finger.

Since rolling friction is much less than sliding friction, in technology they try to replace sliding bearings with ball or roller bearings. Even in an ordinary adult bicycle, there are ball bearings in the wheel hubs, in the steering column, on the crank axle, on the pedal axles.
Cars, motorcycles, tractors, railroad cars - all these machines roll on ball and roller bearings.

REST FRICTION

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 if this force is slightly weakened - 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, matchbox, eraser, etc.

The friction force of motion (under other identical conditions) is usually less than the friction force of rest. In this case, she was unable to hold the pencil on the inclined plane.
By the way, think about why it is easier to pull a nail out of the board if you rotate it around its axis?

ACROBAT WHEEL GOES

Before we finish talking about friction, let's make one more fun toy.
Cut out an acrobat figure from thick paper. Put it on a pen inserted on a sharply sharpened round pencil. A day is now a pencil with an acrobat obliquely into the ring of scissors. Holding the scissors horizontally, move them gently in a circle.

Ah, how our acrobat went wheel!
He's involved in two movements at once. First, the end of the pen with the acrobat on the nib describes large circles. And secondly, the handle does not slide along the ring of the scissors, but rolls over it. And the handle, together with the acrobat, rotates around its axis. From the combination of these two movements, such wonderful wheels are obtained. A living acrobat will hardly be able to repeat them!

Where is the friction, you ask?
Yes, in the ring of scissors. If it were not there, the handle would immediately fall down, it would not be able to hold even in an inclined position. And one more thing: if there was no friction between the ring and the handle, the handle would not run around the ring and the acrobat would not tumble so beautifully.

BRAKE IN THE EGG

Experience 1

Hang a raw egg on a thin string. To prevent the string from slipping off the vertically placed egg, use adhesive tape by sticking small pieces of it on the places where the string is located.

Hang a hard-boiled egg nearby. Twist each string with the egg in one direction for the same number of turns. When the laces are twisted, release the eggs at the same time. You will see that a boiled egg behaves differently than a raw one: it spins much faster.

In a raw egg, its protein and yolk try to remain stationary (this is their inertia) and, by their friction against the shell, slow down its rotation.

In a boiled egg, the protein and yolk are no longer liquid substances and represent, together with the shell, as if one whole, so there is no braking and the egg rotates faster.

This experiment can be done without hanging the eggs: just twist them with your fingers on a large plate.

Experience 2

It is even more interesting to do such an experiment.
Take two identical saucepans with two ears (you can also use toys). Connect the ears with a rope or thin wire, and tie another rope to the middle so that the pan is in balance. Hang both pots on these ropes and pour water into one of them, and the same amount of cereal in the other. Now twist the ropes on the same number revs and release. The result will be similar to the experiment with eggs.

When the pans have spun, try to quickly stop them, and then release them again. It turns out that the pot of water continues to rotate. Well, how can you explain this phenomenon?

Sources: F. Rabiz "Experiments without instruments"; "Funny Physics" L. Galpershtein

1. Introduction

The purpose of this work– to study issues related to the occurrence of friction. This topic, which seems to be well-known for a long time, remains relevant, since the question of the force of friction has not been completely resolved by either physicists or mathematicians, while friction is one of critical issues, for example, for mechanical engineering. A task work - to conduct experiments that allow us to investigate what the friction force depends on. In this way, object of study is friction.

Hypothesis : a world without friction would be unrecognizable and terrible. There would be no development of civilization, because our ancestors used it to extract the fire . Technical progress in the absence of a wheel, it was supposed to become something else.It is also possible that friction is one of the sources of the Earth's internal heat.

Practical significance work is that it is devoted to the theory of friction, which is still not complete. But in order to attract new future researchers, they need to be interested in the problem. And for this you can use the material of this work.

The novelty of the work will be the hypothesis about the reduction of molecular friction under large mountain ranges due to high pressure. And this should lead to an increase in their mobility. That is, to increase the possibility of earthquakes.

2. Basic questions of the theory of friction

2.1. A world without friction

Let's first fantasize a little and imagine what would happen if the friction disappeared? A moving car will not be able to stop, and a stationary one will not be able to move. Pedestrians will fall on the asphalt and will not be able to get up. Also where the floor is below. they suddenly turn out to be naked, as the threads in the fabrics are held by friction. All the furniture in the room will slide into one corner. Plates and glasses will also slide off the table. Nails and screws will pop out of the walls. Not a single thing can be held in hand. Taking and turning the page of the book will also become a problem.

It is interesting to think up and talk about the instantaneous strong decrease in friction in the book for children "The Island of Inexperienced Physicists". “All parts of the car based on the use of friction - brakes, clutch, drive belt - stopped working, and those parts for which friction was a hindrance began to move even faster. Therefore, the engine continued to work and even increased the number of revolutions - the friction in the cylinders and bearings no longer slowed it down ... ". But the car could not move, as the friction between the tires and the asphalt disappeared. Thus, the wheels spun, and the car stood still. The description of the same world is given in the poem:

In this is what the famous Swiss physicist, laureate Nobel Prize Charles Guillaume: “Imagine that friction can be completely eliminated. Then no bodies, whether they are as large as a stone block or as small as a grain of sand, will ever rest on one another: everything will slide and roll until it is on the same level. If there were no friction, the Earth would be a ball without bumps, like a liquid.

2.2. Two causes of friction

The two most important inventions - the wheel (Fig. 1) and making fire (Fig. 2) - are connected precisely with the desire to reduce or increase the effect of friction.

Friction is the result of many causes. The main ones are two. First, the notches of one surface cling to the roughness of the other. This so-called geometric friction (Fig. 3). Secondly, molecular friction when the surfaces of both bodies are sufficiently smooth. In this case, the attraction between their molecules begins to affect (Fig. 4). The science that studies friction is called tribology (from the Greek "tribos" - friction). Friction - mechanical resistance to movement that occurs at the point of contact of two bodies pressed against each other when they move one relative to the other. Resistance force F, directed opposite to the movement of the body, is called the friction force. The laws of dry friction were formulated in 1781 by Sh. O. Coulomb (1736 - 1806). They were determined empirically. But long before that, among the countless scientific and creative achievements of Leonardo da Vinci was the formulation of the laws of friction. Amonton and Coulomb introduced the concept friction coefficient as the ratio of friction force to load. This coefficient determines the friction force for any pair of contacting materials. Denoted by a Greek letter μ [mu]. So far the formula is:

F tr =µР,

where P - pressing force or body weight, a F tr - friction force, is main formula. Her variant:

F tr =μN ,

where N – support reaction force. . N =R. Drawings, which show all the forces acting on the bar, see fig. five.

The coefficient of friction depends not only on which materials are in contact, but also on how smooth the contact surfaces are. More precisely, the formula can be written, taking into account molecular friction:

F = μ (N + S p 0 ),

where R 0 - additional pressure caused by the forces of molecular attraction.

2.3. Types of friction

There is friction at rest, sliding and rolling. It turned out that usually the force of sliding friction at slowmovement is less than the static friction force (that is, starting off). pendant studiedthe force of friction during slow motionbodies and found that this force does not depend onspeed, but only on the direction of movement.The smallest is rolling friction. Therefore, when moving heavy objects (ships on land, stone blocks for construction), people placed skating rinks (ordinary logs) under them. A round object (such as a barrel) is easier to roll than to drag. The use of bearings in technology is also based on this: ball and roller bearings (Fig. 6).

Another example from practice, about the differences in the use of types of friction: if the car brakes by sliding (skidding), then the braking distance is longer than during rolling braking, when the wheel rotates and its surface clings well to the road surface. This should be remembered by both the driver and the pedestrians crossing the street!

3. Modern painting friction

As one of the founders of the science of friction, F. Bowden, figuratively put it, “the imposition of two solid bodies one on top of the other is similar to the imposition of the inverted Swiss Alps on the Austrian Alps - the contact area turns out to be very small” (Fig. 7). Photographs of various surfaces taken with microscopes confirm the comparison with mountains (Fig. 8.9). When trying to move, the pointed "mountain peaks" cling to each other and crush their peaks. When trying to shift in a horizontal direction, one peak begins to bend the other, that is, it first tries to smooth the road (Fig. 10 a), and then slides along it (Fig. 10 b). If you pull the body with a dynamometer with constant speed, thenit turns out that the body itself is moving in jerks. Dthe movement turns out to be oscillatory: sticking and sliding alternately replace each other.

4. vibration smoothing

Sometimes it is important to avoid jerky movement. For example, a welding robot must smoothly guide the welding machine along the weld. If it twitches, then in one place there will be overheating and the plates being welded will be distorted, and in another - welding will not occur at all, since the device will jump forward too quickly. Vibrational smoothing can serve as one of the ways to combat these jerks. Under the action of fast vibrations, dry friction begins to resemble liquid friction, since the particles touch each other worse due to shaking and bulk material from solid particles begins to behave like a liquid. And in particular, it can move easily. And here, too, there may be negative examples. Crossing Lake Ladoga on stormy autumn days, some ships carrying grain began to sway violently from side to side and capsized. It turned out that the designers believed that the grain in the hold would lie motionless due to dry friction, linking individual grains to each other. But the vibrations made the bulk material look like liquid. The grain began to behave like a liquid, leaning on the sloping side of the ship during transportation, causing it to capsize. As soon as the effect was understood, the holds were divided into compartments, as in those ships that carry real liquids.

5. Fluid friction

When a solid body moves in a liquid or gas, the resistance force of the medium acts on it, which can be considered a special type of friction force. This force is directed against the movement of the body and slows it down. main feature resistance force is that it occurs only when the body moves. It depends on his body speed, as well as on the shape and size. Therefore, for example, cars are given a streamlined shape, especially racing ones. In addition, the resistance force depends on the state of the surface of the body and the viscosity of the medium in which it moves. In liquids and gases, there is no static friction force.

Liquid friction is much less than dry friction, since liquid molecules can easily move relative to each other. Therefore, lubrication is successfully used to reduce friction.

5.1. Wear. Lubricant

As a result of friction, the parts of the mechanisms are worn out and the surfaces are destroyed. Lubrication is one way to combat wear.In this case, both friction surfaces are covered with protective films of lubricant molecules.The coefficient of friction is reduced. This happens because mthe molecules of a liquid are attracted to each other weaker than the molecules of a solid. Therefore, in the presence of lubrication between the rubbing surfaces, they easily slide relative to each other.Currently being developedpreparations that allow during operation, without making a complete disassembly of components and assemblies, to partially restore wornfriction surfaces with a simultaneous increase in their wear resistance.

5.2. aquaplaning

Hydroplaning looks like this: on a wet road, the tire slides through the water like a glider, that is, the contact of the wheel with the road disappears. The car loses control. Studies have shown that as the speed increases, a water roller appears in front of the wheel, and a water wedge appears below. As the speed increases, the effect increases. At the same time, the car does not move on asphalt, but, as it were, “floats” on water (Fig. 11).

In addition to studying the theoretical material, the authors of the work conducted a number of experiments that make it possible to independently determine F tr and the dependence of the friction coefficient on certain physical quantities or conditions. See the appendix for the results.

Comparison of the friction force of rest, sliding and rolling (Table 1). Photo.1,2.

Investigation of the dependence of the friction force on the contact area. For this purpose, the bar in the second experiment was placed on the other side (table 2). A photo. 3.

The dependence of the friction force on the load (the weight of the bar and loads) or otherwise on the reaction force of the support N (Table 3).

Dependence on the type of substance and the processing conditions of two surfaces (Tables 4-7).

Sida Friction F tr (or coefficient of friction  ) is practically independent of speed at low relative speeds of movement of the contacting surfaces. But according to the studied theoretical materials as the speed increases, the friction force decreases slightly.

General conclusions:

Friction force F tr practically does not depend on the contact area and speed (at low speeds).

Friction force F tr depends on the load (N \u003d P), on the type of substance and surface treatment conditions. Typically, friction coefficients range from 0.1 to 1.05 (0.1 1.05).

The value of the friction force in decreasing order: friction of rest, sliding, rolling. F tr rest  F tr sk.  F tr qual.

7. Regional component

In September 2002, the Kolka glacier descended in North Ossetia. The ice-mud-stone stream advanced almost 20 km along the Genaldon River valley at a speed of about 150-200 km / h, destroying buildings, recreation centers, and power lines. The main assumptions about the causes of this catastrophe are that there was a sudden shift due to a complex of seismic, volcanic and meteorological causes. This glacier belongs to the category of pulsating. At the time of the disaster, he was not yet "ripe" for the fall. This was confirmed by the data of filming from space. Thus, the static friction forces held the entire mass of the glacier, but as a result external influence like an impact or explosion on the entire mass of snow, a process similar to vibrational smoothing occurred. Scheme of the process: impact, the particles rose up, the load P decreased and, consequently, the friction also became less.

When some bodies move on the surface of others, friction occurs. This happens when the roughness of one surface clings to the roughness of another, or when smooth surfaces begin to stick to each other due to intermolecular attraction. But, as you know, between molecules there is not only mutual attraction. If the molecules are too close to each other, they will repel each other. The hypothesis is as follows: very heavy lithospheric plates with the mainland and mountain systems exert such an enormous pressure on the underlying layers that the repulsion of molecules begins to affect. This leads to additional mobility of loaded areas of the plate, compared to less loaded and, therefore, less mobile margins. The result will be the impossibility of the movement of the entire complex as a whole. In this case, additional loads of individual areas will appear, which can lead to earthquakes that relieve the resulting mechanical stresses.

9. Conclusion

In the USA alone, 1,000 researchers are currently working on this topic, and more than 700 articles are published annually in world science. But as wittily pointed out famous physicist R. Feynman - all of our measurements to determine the coefficients of friction are actually considerations of mud-on-mud friction cases. microscopes various designs show the complexity of the problem. Figure 11 shows an atomic force microscope. Even for him, there is a problem, which consists in the fact that in air the surface of the sample is covered with water vapor up to 20-30 molecules thick. In this way, this topic allows many researchers to work on it for many years to come. And the authors of this work also managed not only to conduct standard experiments and verify the accuracy of the already known information about the friction force, but also to express their own opinion. scientific hypothesis on the role of molecular friction.

10. Literature

Agayan V. Dazen N. What happens if friction disappears?// Kvant. No. 5. 1990.

Dombrovsky K. I. Island of inexperienced physicists. - M .: Children's literature, 1973.

Pervozvansky A.A. Friction is a familiar but mysterious force.//Soros Educational Journal. No. 2.1998.

Peryshkin A.V. Physics - 7. - M ..: Bustard, 2008.

Matveev A. Tribonics or a drop of lubricant.// Young Technician, №1.1987.

Kravchuk A.S. Friction. "Modern Natural Science", v.Z.M.: Magister -Press. 2000.

7. Solodushko A.D. Experiment in the study of the force of friction.//Physics at school. №5.2001

22.04.2016 09:30

Job title:

MBOU "OOSH №4"

Town: Troitsk

The relevance of this topic:

The purpose of my work:

Tasks:

Research methods:

Object of study:

Subject of study:

"The Force of Friction Project"

Department of Education of the Troitsk City Administration

Urban Research Conference

students in grades 5-8 municipal educational institutions

"First Steps in Science"

Investigation of the coefficient of friction of shoes

about different surface

I've done the work:

student of MBOU "OOSH No. 4"

Butorin Gleb, Grade 7

Head: physics teacher

Kovalenko Inna Sergeevna

Troitsk, 2015

	Introduction
	Research Article
	Theoretical part
	Practical part
	Experience 1. Determination of the coefficients of friction and the dependence of the friction force on the materials of the surfaces.

	Conclusion
	Bibliography

annotation

Target scientific work:

Knowing the coefficient of friction of the sole material on a different surface, you can choose best option purchasing shoes. Methods used in the work: questioning, physical experiment, mathematical calculation, analysis of results. After conducting the experiment, I concluded that the highest coefficient of friction for a sole made of polyurethane, then rubber, rubber, and the smallest coefficient for plastic. It follows from this that when buying shoes, one should take into account the features of the soles and weather in which you will wear shoes.

Introduction

Relevance

AT winter time When there is ice on the street, there are a lot of falls and injuries.

Therefore, it is very important when buying shoes to take into account the characteristics of the soles and the weather conditions in which you will wear these shoes. This is where the relevance lies.

Problem

Objective

Study of the friction of shoe soles made from different materials o various surfaces and determining the most practical materials for their manufacture.

Tasks:

1. Explore theoretical basis dry friction.

2. Conduct a survey among students to identify the most popular shoe manufacturers, the level of awareness about the sole material and the effect of the sole material on friction when walking.

3. Measure the sliding friction coefficient of the shoe sole material on a different surface.

4. Analyze the obtained measurement results and identify the most appropriate options for using shoes.

Research methods

1. Questioning.

2. Physical experiment.

3. Mathematical calculation.

4. Analysis of the results.

Object of study

Subject of study

Hypothesis

II . Research Article

1. Theoretical part

Resistance to motion arises when one body slides over the surface of another. If solid surfaces or solid interlayers between bodies (oxide films, polymer coatings) come into contact, friction is called dry.

Friction takes part (and, moreover, very significant) where we are not even aware of it. But do not think that friction always prevents movement - often it contributes to it.

Features of friction forces:

Occur on contact

Act along the surface;

Always directed against the direction of movement of the body.

What determines the magnitude of the dry friction force? Everyday experience shows that the stronger the surfaces of bodies are pressed against each other, the more difficult it is to cause their mutual sliding and maintain it (for example, a sheet of paper inserted between the pages of a thick book lying on the table is easier to pull out from the top than from the bottom). The pressing force acting from the neighboring body on the rubbing surface is perpendicular to it and is called the force of normal pressure.

F tr \u003d µN; N = F strand

µ - coefficient of friction - determined by the roughness of the contacting surfaces; for smoother surfaces it is smaller. For example, after being hit with a hockey stick, a sliding puck stops faster on a wooden floor than on ice.

2. Practical part

question number	Quantity	%, percentage of total number
	Unichel - 5 "Monroe" - 8 "Curry" - 7 "Shoes for All" - 6 Russian manufacturers - 6 Manufacturer unknown - 22

Questionnaire

The next stage of the work was to measure the coefficient of sliding friction of shoe soles when interacting with various surfaces.

3. Experience 1

The experiment was carried out in stores and at home. The experiment was as follows: I pulled the shoes attached to the dynamometer evenly along various surfaces, took the readings of the dynamometer in this position, and also measured the gravity of this shoe;

Instruments and materials used in the experiment:

3.Dynamometer.

The order of the experiment:

Friction against laminate

Shoe firm	sole material	surface material	F heavy, N (average value)	F tr., N (average value)	coefficient of friction μ

Shoes for everyone	polyurethane

Unichel (plastic)

Shoes for everyone (polyurethane)

Curry (rubber)

Monroe (rubber)

Calculation of the coefficient of friction when the shoes rub against the laminate: µ=

Plastic µ=1.03 N: 2.6N=0.39

Polyurethane µ=1.46 H:2.4H=0.6

Rubber µ=1.1N:2.2 N=0.5

Rubber µ=1.4 N:3.3 N=0.42

Friction on cement

Shoe firm	sole material	surface material	F heavy, N (average value)	F tr., N (average value)	coefficient of friction μ

Shoes for everyone	polyurethane

Unichel (plastic)

Shoes for everyone (polyurethane)

Curry (rubber)

Monroe (rubber)

Calculation of the coefficient of friction when shoes rub against cement: µ=

Plastic µ=0.46 N: 2.6N=0.18

Polyurethane µ=0.7 N:2.4N=0.3

Rubber µ=0.6N:2.2 N=0.27

Rubber µ=0.83N:3.3 N=0.25

Carpet friction

Shoe firm	sole material	surface material	F heavy, N (average value)	F tr., N (average value)	coefficient of friction μ

Shoes for everyone	polyurethane

Unichel (plastic)

Shoes for everyone (polyurethane)

Curry (rubber)

Monroe (rubber)

Calculation of the coefficient of friction when the shoes rub against the carpet: µ=

Plastic µ=1.6 N: 2.6N=0.62

Polyurethane µ=2.4 N:2.4N=1

Rubber µ=1.76N:2.2 N=0.8

Rubber µ=2.6N:3.3 N=0.78

1. All interviewed respondents are aware of the effect of sole material on friction when walking, but most of them are not interested in the sole material when buying shoes.

2. The value of the coefficient of friction of the material of the soles of popular manufacturers corresponds to allowed values.

1. All interviewed respondents are aware of the effect of sole material on friction when walking, but most of them are not interested in the sole material when buying shoes.

highest value made of polyurethane, rubber and rubber

The ideal option is to offer shoes with rubber and polyurethane soles.

III . Conclusion

IV . Bibliography:

1. Aksyonova M., Volodin V. Encyclopedia "Physics": "Avanta", 2005.

2. S.V. Gromov, N.A. Rodina "Physics": Moscow "Enlightenment", 2000.

3. N.M. Shakhmaev, S.N. Shakhmaev, D.Sh. Chodiev "Physics": Moscow "Enlightenment", 1995.

4. A.V. Peryshkin, E.M. Gutnik "Physics": Moscow "Drofa", 2003.

5. O.F.Kabardin “Physics. Handbook for high school students»; AST-PREES, Moscow, 2005.

View document content
"Thesis Friction Force"

Job title: The study of the coefficient of friction of shoes on a different surface

educational institution: MBOU "OOSH №4"

Town: Troitsk

Hello, dear members of the jury and participants of the conference. Allow me to present a work on the topic: "Investigation of the coefficient of friction on a different surface" The relevance of this topic: In winter, when there is ice on the street, there are a lot of falls and injuries. Therefore, it is very important when buying shoes to take into account the characteristics of the soles and the weather conditions in which you will wear these shoes. This is where the relevance lies.

The research problem was that when buying shoes, few people pay attention to the material from which the sole is made and does not take into account the coefficient of friction of shoes on various surfaces.

The purpose of my work: The study of the friction of shoe soles made of different materials on different surfaces and the determination of the most practical materials for their manufacture.

Tasks:

1. To study the theoretical foundations of dry friction.

2. Conduct a survey among students to identify the most popular shoe manufacturers, the level of awareness about the sole material and the effect of the sole material on friction when walking.

3. Measure the sliding friction coefficient of the shoe sole material on a different surface.

4. Analyze the obtained measurement results and identify the most appropriate options for using shoes.

Research methods: Questioning, physical experiment, mathematical calculation, analysis of results.

Object of study: Winter shoes with rubber, polyurethane, rubber and plastic soles, which are sold in stores in our city.

Subject of study:

The hypothesis that was put forward:

The nature of the friction force is electromagnetic. This means that the cause of its occurrence is the interaction forces between the particles that make up the substance. The second reason for the friction force is the surface roughness. Due to the unevenness of the surface, they touch each other only at certain points located on the tops of the protrusions. Here, the molecules of the bodies in contact approach at distances commensurate with the distances between the molecules, and interlock. A strong bond is formed, which breaks when pressed against the body. When the body moves, the bonds constantly arise and break. The protruding parts of the surfaces touch each other and prevent the movement of the body. That is why, for movement on smooth (polished) surfaces, less force is required than for movement on rough ones.

Friction force acting along the contact surface solids, directed against the slip of the body.

Friction contributes to stability. The carpenters level the floor so that the tables and chairs stay where they are. Dishes, glasses, put on the table, remain motionless without any special care on our part, unless it happens on the ship during the pitching.

Imagine that friction can be eliminated completely. Then no bodies, whether they are the size of a stone block or small as grains of sand, will ever rest on one another. If there were no friction, the Earth would be a ball without irregularities, like a liquid drop.

What determines the magnitude of the dry friction force?

Everyday experience shows: the stronger the surfaces of bodies are pressed against each other, the more difficult it is to cause their mutual sliding and maintain it. The pressing force acting from the side of the neighboring body on the rubbing surface is perpendicular to it and is called the force of normal pressure.

In 1781, Charles Coulomb, studying the friction of parts and ropes, which at that time were essential parts of mechanisms, experimentally found that the friction force F TP is directly proportional to the pressing force N:

F tr \u003d µN; N = F strand

The coefficient of proportionality µ - coefficient of friction - is determined by the roughness of the contacting surfaces; for smoother surfaces it is smaller.

In order to identify the most popular shoe manufacturers and the level of awareness about the properties of the sole material and the effect of the sole material on friction when walking, a survey was conducted among teachers and students of our school.

54 students and teachers took part in the survey. When processing the survey data, it turned out that the most popular shoe manufacturers are Monroe (14.8%), Curry (13%), Footwear for All (11%), Unichel (9.3%). Many (40.7% of respondents) do not know shoe manufacturers, because they buy shoes in the markets, often handicrafts. All respondents (100%) are aware that the material of the sole significantly affects the friction when walking, but when buying shoes, few people are interested in what material the sole is made of (78%). When asked about awareness of physical properties sole material 90.7% answered negatively.

The purpose of the experiment is to study the dependence of the friction force of the shoe sole on a different surface on the pressure force and surface materials, to determine the coefficients of friction.

For this experience used the following tools and materials:

1.Shoes with rubber soles, polyurethane, plastic and rubber soles.

2. Carpet, cement surfaces and laminate.

3.Dynamometer.

It should be borne in mind that if the sole is called rubber, then it does not consist of 100% rubber, it contains many other elements in its composition, but the rubber content prevails in it. Also with rubber, plastic and polyurethane soles.

The experiment was carried out in the following order:

Measured the force of gravity acting on a boot with a rubber sole. To do this, hung it on a dynamometer.

I put this rubber-soled boot on a carpeted surface and held it out with uniform speed on the carpet for about a meter, taking the dynamometer reading in this position.

I repeated the experiment, calculated the average value of the friction force to obtain more accurate results, calculated the coefficient of friction.

He ran his boot over cement, wood, and laminate and took a reading from the dynamometer.

I repeated the experiments and calculated the average value of the friction force to obtain more accurate results, calculated the coefficient of friction.

The data obtained was entered into tables.

Thus, after conducting the experiment, I concluded that the sole made of polyurethane has the highest friction coefficient, then rubber and rubber, and the plastic has the lowest coefficient. From this it follows that when buying shoes, you should take into account the characteristics of the soles and the weather conditions in which you will wear shoes. In winter, it is better to buy shoes with polyurethane soles, as they have the highest coefficient of friction on various surfaces (seen from the diagram), this will help to avoid falls and injuries in winter, when there is ice on the street. Polyurethane also has good resistance to various temperatures and strength. It is not advisable to buy shoes with plastic soles in winter.

Thank you for your attention!

"Friction Force 1"

I've done the work:

Student of MBOU "OOSH No. 4"

Butorin Gleb, 7th grade

Head: physics teacher

Kovalenko Inna Sergeevna

Objective:

3. Measure the sliding friction coefficient of the shoe sole material on a different surface.

1. Questioning.

2. Physical experiment.

3. Mathematical calculation.

4. Analysis of the results.

Friction

Charles Pendant

Day birth : 14.06 . 1736 of the year

Date of death: 28.08 . 1806 of the year

F = µN,

where N = mg

µ- proportionality factor

or coefficient of friction

Question number

Quantity

%, percentage of total

Unichel - 5

"Monroe" - 8

"Shoes for All" - 7

"Curry" - 6

Russian manufacturers - 6

Manufacturer unknown - 22

1. Which brand of shoes do you wear?

2. Did you know that the material of the sole significantly affects the friction when walking?

3. When buying shoes, are you interested in what material the soles of the shoes are made of?

4. Do you know about the physical properties and characteristics various materials to make soles?

Using the results obtained, he calculated the coefficients of friction of different shoes on different surfaces.

F = µN,

where N = mg

µ- proportionality factor

or coefficient of friction

Friction against laminate

Shoe firm

sole material

Shoes for everyone

surface material

(average value)

polyurethane

F tr., N (average value)

coefficient of friction μ

Calculation of the average value of the friction force on the laminate

Unichel (plastic)

Shoes for everyone (polyurethane)

Monroe (rubber)

Unichel (plastic) μ

Shoes for everyone (polyurethane)

Curry (rubber)

Monroe (rubber) μ

Friction on cement

Shoe firm

sole material

surface material

Shoes for everyone

(average value)

polyurethane

F tr., N (average value)

coefficient of friction μ

Unichel (plastic)

Shoes for everyone

(polyurethane)

Curry (rubber)

Monroe (rubber)

Unichel (plastic)

Shoes for everyone (polyurethane)

Curry (rubber)

Monroe (rubber)

Carpet friction

Shoe firm

sole material

Shoes for everyone

surface material

polyurethane

F tr., N (average value)

coefficient of friction μ

2. The material of the sole significantly affects the value of the coefficient of friction. highest value coefficient of sliding friction has a sole made polyurethane , rubber and rubber, and the smallest - made of plastic.

3. Knowing the coefficient of friction of the sole material on a different surface, you can choose the best option for purchasing shoes. As

The goal has been reached.

Thank you for your attention!

And don't fall!

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"Friction force"

RESEARCH WORK IN PHYSICS "RESEARCH OF THE COEFFICIENT OF FRICTION OF SHOE ON DIFFERENT SURFACE"

I've done the work:

Student of MBOU "OOSH No. 4"

Butorin Gleb, 7th grade

Head: physics teacher

Kovalenko Inna Sergeevna

Relevance

In winter, there are a lot of falls and injuries when there is ice on the street.

Therefore, it is very important when buying shoes to take into account the characteristics of the soles and the weather conditions in which you will wear these shoes.

Problem

Hypothesis

Objective:

The study of the friction of shoe soles made of different materials on different surfaces and the determination of the most practical materials for their manufacture.

Tasks:

1 . To study the theoretical foundations of dry friction.

2. Conduct a survey among students to identify the most popular shoe manufacturers and the level of awareness about the sole material and the effect of sole material on friction when walking.

3. Measure the sliding friction coefficient of the shoe sole material on a different surface.

4. Conduct an analysis of the obtained measurement results and identify the most appropriate options for using shoes.

Object of study

Subject of study

Research methods

1. Questioning.

2. Physical experiment.

3. Mathematical calculation.

4. Analysis of the results.

BY THE PAGES OF HISTORY

Charles Pendant conducted a series of experiments in which he studied key features friction phenomena.

The scientist, on the basis of his experiments, refined the laws of friction, first formulated by Amonton, established and considered the presence of an intermolecular component of the friction force (although he considered the engagement of irregularities to be the main factor). Coulomb also established the dependence of the static friction force on the duration of the preliminary contact of the bodies.

For the best solution of friction problems in 1781, the scientist received a prize of 2,000 livres from the French Academy of Sciences.

Day birth : 14.06 . 1736 of the year

Date of death: 28.08 . 1806 of the year

Theoretical part

Friction- the process of interaction of solid bodies during their relative motion (displacement) or during the motion of a body in a gaseous or liquid medium.

The emergence of friction force

Survey results (54 respondents)

Question number

Quantity

Unichel - 5

%, percentage of total

"Monroe" - 8

"Shoes for All" - 7

"Curry" - 6

Russian manufacturers - 6

Manufacturer unknown - 22

1. Which brand of shoes do you wear?

2. Did you know that the material of the sole significantly affects the friction when walking?

3. When buying shoes, are you interested in what material the soles of the shoes are made of?

4. Do you know about the physical properties and characteristics of different sole materials?

My research

The experience was as follows: I pulled the shoes attached to the dynamometer evenly along various surfaces, took the dynamometer readings in this position.

My research

And also measured the gravity of this shoe. hung it on a dynamometer.

Using the results obtained, he calculated the coefficients of friction of different shoes on different surfaces.

FORMULA FOR DETERMINING THE FORCE OF FRICTION I AM

F = µN,

where N = mg

µ- proportionality factor

or coefficient of friction

Friction against laminate

Shoe firm

sole material

Shoes for everyone

surface material

polyurethane

Ftr., N (average value)

(average value)

coefficient of friction μ

Calculation of the average value of the friction force on the laminate

Unichel (plastic)

Shoes for everyone (polyurethane)

Monroe (rubber)

Calculation of the coefficient of friction when the shoes rub against the laminate

Unichel (plastic) μ

Shoes for everyone (polyurethane)

Curry (rubber)

Monroe (rubber) μ

Diagram "Coefficient of friction on laminate"

Friction on cement

Shoe firm

sole material

surface material

Shoes for everyone

polyurethane

Ftr., N (average value)

(average value)

coefficient of friction μ

Calculation of the average friction force on cement

Unichel (plastic)

Shoes for everyone

(polyurethane)

Curry (rubber)

Monroe (rubber)

Calculation of the coefficient of friction when shoes rub against cement

Unichel (plastic)

Shoes for everyone (polyurethane)

Curry (rubber)

Monroe (rubber)

Diagram "Coefficient of friction on cement"

Carpet friction

Shoe firm

sole material

Shoes for everyone

surface material

polyurethane

Ftr., N (average value)

coefficient of friction μ

Diagram "The coefficient of friction on the carpet"

Diagram of dependence of the sliding friction coefficient of the sole material on the type of surface

1 . All respondents are aware of the effect of sole material on friction when walking, but most of them are not interested in the sole material when buying shoes.

3. Knowing the coefficient of friction of the sole material on a different surface, you can choose the best option for purchasing shoes. As ideal option you can offer shoes with rubber and polyurethane soles.

The goal has been reached.

Thank you for your attention!

And don't fall!

Relevance: The work is intended to form a worldview about reality. Answers to many important questions associated with the motion of bodies give the laws of friction. The relevance of the topic is that it connects theory with practice, reveals the possibility of explaining the nature, application and use of the studied material. this work allows to develop creative thinking, the ability to acquire knowledge from various sources, analyze facts, conduct experiments, make generalizations, express one's own judgments, think about the mysteries of nature and look for a path to the truth.

trace historical experience humanity on the use and application of this phenomenon; find out the nature of the phenomenon of friction, the laws of friction; conduct experiments confirming the regularities and dependences of the friction force; perform demonstration experiments proving the dependence of the friction force on the force of normal pressure, on the properties of the contacting surfaces. Tasks:

Mow, spit, while dew, dew down - and you're home. If you don't, you won't go. Things went like clockwork. It will fit into the soul without soap. Ride like cheese in butter. From that the cart sang that it had not eaten tar for a long time. Proverbs are explained by the existence of friction and the use of lubricant to reduce it.

still water washes away the banks. Between the individual layers of water flowing in the river, there is friction, which is called internal. In this regard, the speed of water flow in different areas cross section the riverbed is not the same: the largest is in the middle of the channel, the smallest is near the banks. The friction force not only slows down the water, but also acts on the shore, pulling out soil particles and, thereby, washing it away.

3. The history of the study of friction by Leonardo da Vinci Euler Leonard Amont Coulomb Charles Augustin de

Year Scientist's name DEPENDENCE of the sliding friction force modulus on the area of contacting bodies on the material on the load on the relative speed of movement of rubbing surfaces on the degree of surface roughness 1500 Leonardo da Vinci No Yes NoYes 1699Amonton No Yes No 1748 Leonhard Euler No Yes 1779Coulomb Yes 1883N.P.Petrov NoYes

Conclusion: The force of sliding friction depends on the load than more load, the greater the friction force. Experimental results: 1. Dependence of the sliding friction force on the load. m (g) F tp (N) 0.50.81.0

When we tie a belt Without friction, all the threads would slip out of the fabric. Without friction, all the knots would have untied. Without friction, it would be impossible to take a step, and, in general, to stand. Friction takes part where we do not even suspect it Conclusion When we sew When we walk

We found out that a person has long been using knowledge about the phenomenon of friction, obtained empirically. We have created a series of experiments to help understand and explain some difficult observations. The force of friction occurs between contacting surfaces. The force of friction depends on the type of surfaces in contact. The force of friction does not depend on the area of the rubbing surfaces. The friction force decreases when sliding friction is replaced by rolling friction, when rubbing surfaces are lubricated. Conclusions based on the results of the work:

Relevance: The work is intended to form a worldview about reality. The laws of friction provide answers to many important questions related to the motion of bodies. The relevance of the topic is that it connects theory with practice, reveals the possibility of explaining the nature, application and use of the studied material. This work allows you to develop creative thinking, the ability to acquire knowledge from various sources, analyze facts, conduct experiments, make generalizations, express your own judgments, think about the mysteries of nature and look for a path to the truth.

To trace the historical experience of mankind in the use and application of this phenomenon; find out the nature of the phenomenon of friction, the laws of friction; conduct experiments confirming the regularities and dependences of the friction force; perform demonstration experiments proving the dependence of the friction force on the force of normal pressure, on the properties of the contacting surfaces. Tasks:

Quiet water washes away the banks. Between the individual layers of water flowing in the river, there is friction, which is called internal. In this regard, the speed of water flow in different parts of the cross section of the river channel is not the same: the highest is in the middle of the channel, the smallest is near the banks. The friction force not only slows down the water, but also acts on the shore, pulling out soil particles and, thereby, washing it away.

3. The history of the study of friction by Leonardo da Vinci Euler Leonard Amont Coulomb Charles Augustin de

Conclusion: The sliding friction force depends on the load, the greater the load, the greater the friction force. Experimental results: 1. Dependence of the sliding friction force on the load. m (g) F tp (N) 0.50.81.0

The force of friction is an interesting experiment. Calculation of the average value of the friction force on the laminate

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View document content
"Thesis Friction Force"

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"Friction force"