Where levers are used in everyday life technology. Research paper in physics about the lever

To the question Levers in technology, everyday life and nature. Give a few examples. given by the author MASHENKA the best answer is

mechanisms like:
inclined plane,
with blocks,
also use a wedge, a screw.

Examples:

In everyday life: scissors, wire cutters.
In nature: in man himself.

Answer from hospitality[newbie]
I don't know

Answer from Ўriy Korop[newbie]
Levers in technology, everyday life and nature.
LEVER, the simplest mechanism that allows a smaller force to balance a large one;
represents solid revolving around a fixed support.
The lever is used to obtain more force on the short arm using
less force on the long arm (or to get more movement on
long arm with less movement on the short arm). Having made a shoulder
lever long enough, theoretically, you can develop any effort.
In many cases in Everyday life we use the simplest
mechanisms like:
inclined plane,
with blocks,
also use a wedge, a screw.
Tools such as a hoe or a paddle were used to reduce the force
that had to be applied to a person. Steelyard, which allowed to change
force application shoulder, which made the use of scales more convenient. Example
compound lever used in everyday life can be found in tweezers
for nails. Cranes, motors, pliers, scissors, and thousands
other mechanisms and tools use levers in their design.
Examples:
Technique: piano, typewriter.
In everyday life: scissors, wire cutters.
In nature: in man himself.

Answer from flush[active]
for example, a swing or a scissors control lever, our hands are also levers, and also our legs, more precisely, our whole body is like a lever in birds or mammals, well, or artiodactyls of the cat family of the canine family for everyone

Answer from brushwood[newbie]
An example of the simplest levers are scissors, wire cutters, scissors for cutting metal, pliers, a chisel, a chisel, a crowbar, the use of a carpenter's hammer (has a bifurcated back), for pulling out nails.
Levers different kind available on many machines: handle sewing machine, bicycle pedals or handbrake, piano keys are all examples of levers. Crane, excavator, wheelbarrow, catapult, well gate and many other devices use the lever rule.
Libra is also an example of a lever.

"First Steps in Science"

Municipal budgetary educational institution average comprehensive school with in-depth study of individual subjects No. 32 Samara

Section: Physics

Subject:“There is power! Mind is not necessary?

Abramov Danila,

4B class student

MBOU secondary school No. 32

g.o. Samara

Work manager

Zibert Galina Ivanovna,

teacher primary school

Samara, 2015

Table of contents

I. Introduction ……………………………………………………………………..3

II. Main part. The lever and its varieties……………………………...5

III. Practical part…………………………………………………..…..11

3.1 Levers in technology and everyday life …………………………………………………….11

3.2. Laboratory work on the topic

“Clarification of the conditions for the equilibrium of the lever” ……………………...…….12

3.3. Experiments at home ………………………………… 13

3.4. Manufacture of devices and models working on the principle

lever ……………………………………………….…………………...15

IV. Conclusion …………………………….…………………………..….….17

Literature ……………………………………………..………………….…..18

Applications……………………………………………………………………...19

Introduction

Once the whole family went by car to the forest. Everything was just fine, if not for the rain. He made us come back and go home. And, of course, on the rain-soaked road we got stuck. All attempts to push the car were in vain ... And then my dad said: “I wish we now, son, would have some strong man to help us!”. But there were no strong men and heroes nearby, and a tractor drove up. He unwound the winch, tied a cable to our car and pulled it out in 5 minutes.

I always really wanted to be strong, a real helper and be like Russian heroes - kind, honest, strong and dexterous. But then I asked myself the question: “How can some people perform such seemingly impossible tasks for an ordinary person?”

I put forwardhypothesis - most likely, there are mechanisms that help a person become stronger.(See slide 1).

Target research : find out the principle of operation of the simplest mechanisms.(See slide 1).

In search of an answer, I turned to the science of physics. I learned that the strength of the man himself is limited, so he often uses devices to increase the strength of his action.Such devices are called simple mechanisms. These include: the lever and its varieties - block and gate; inclined plane and its varieties - wedge and screw.

Tasks :

1. learn about the origin and types of leverage;

2. conduct experiments with a lever;

3. with the help of adults, simulate devices that operate on the principle of a lever;

4. prepare electronic presentation according to the results of the study.(See slide 1).

An object: lever arm.

Thing: leverage in people's lives.

Methods Keywords: search for information in the literature and the Internet, observation, description and measurement, experimental work,modeling.

II . Lever and its varieties.

"Give me a point of support, and I will move the Earth!"

Archimedes

Man is a rational being. It was the mind that always gave him the opportunity to create devices that made him stronger or faster than the beast, to live in conditions in which he could not survive without these things.

One of the first such devices was the lever. Even primitive man turned an ordinary pole into a tool for lifting weights. By slipping a long stick under the stone and resting it on a piece of wood that served as a support, it was possible to move the stone to another place without any problems. The longer the pole, the easier it is to work. The invention of the lever advanced primitive man along the way of its development.

The hoe and oar were invented by man to reduce the force that had to be applied to perform any work.(See slide 1).

In the fifth millennium BC, Mesopotamia used scales that used the principle of leverage to achieve balance.

Without a lever, it would be impossible to lift the heavy stone slabs when building the pyramids in Ancient Egypt. For the construction of the pyramid of Cheops, which has a height of 147 m, 2,300,000 stone blocks were used, the smallest of which had a mass of 2.5 tons.

Around 1500 BC, the shaduf appears in Egypt and India - the progenitor of modern cranes, a device for lifting vessels with water.In Russia it was also used similar device to raise water from the well and it was called "Crane".

Thus, we do not know the name of the author of the lever, nor exact date his inventions. But we can state with full confidence that ancient people without mathematical rules and laws of physics invented and widely used simple mechanisms, relying on their intuition and experience.

2.2 Archimedes is a mechanic.

Lever, block, inclined plane interested the scientist Archimedes, who lived in Ancient Greece during antiquity. In the III century BC. e. Archimedes gave the first written explanation of the principle of operation of the lever, linking the concepts of force, load and shoulder. The law of equilibrium formulated by him is still used and sounds like:"The lever is in equilibrium when the forces acting on it are inversely proportional to the shoulders of these forces". Archimedes laid out the complete theory of the lever and put it into practice successfully. Plutarch reports that Archimedes built many block-lever mechanisms in the port of Syracuse to facilitate the lifting and transportation of heavy loads. The screw (auger) invented by him for scooping out water is still used in Egypt.Archimedes is also the first theoretician of mechanics. He begins his book On the Equilibrium of Plane Figures with a proof of the law of the lever.(See slide 1).

The legend tells that the heavy multi-deck ship "Syracusia" built by Hieron as a gift to the Egyptian king Ptolemy could not be launched. Archimedes built a system of blocks (polyspast), with the help of which he was able to do this work with one movement of his hand. According to legend, Archimedes said at the same time: “If I had another Earth at my disposal, on which I could stand, I would move ours” (in another version: “Give me a fulcrum, and I will turn the world upside down”).(See slide 1).

The engineering genius of Archimedes manifested itself with particular force during the siege of Syracuse by the Romans in 212 BC. e. during the Second Punic War. But at that time he was already 75 years old!Archimedes created throwing machines capable of throwing stones weighing about 250 kg at high speed and mechanisms that threw heavy logs from the shore onto ships. AT last years Several experiments were carried out in order to verify the veracity of the description of this "superweapon of antiquity". The constructed structure has shown its full performance.

The so-called "Paw of Archimedes" was a unique lifting machine - the prototype of a modern crane. It was a huge lever protruding from the city wall and equipped with a counterweight.(See slide 1).

The famous historian of antiquity, Polybius, wrote that if a Roman ship tried to land near Syracuse, this machine, controlled by a specially trained person, grabbed the bow of the ship and turned it over. The Romans were forced to abandon the idea of taking the city by storm and proceeded to the siege. Polybius wrote: “Such is the miraculous power of one person, one talent, skillfully directed to some business ... the Romans could quickly take over the city if someone removed one elder from among the Syracusans.”

Assessing the role of Archimedes, a mechanic, I would like to note that he made the appropriate calculations and designed more complex mechanisms that could enhance and transform movements. Thanks to Archimedes, mankind learned to launch big ships, build combat vehicles.

2.3 What is a lever.

And yet, a person's strength is limited, so he often uses devices (or devices) that make it possible to transform a person's strength into a force that is significantly greater. A heavy object (stone, cabinet, machine), which cannot be moved directly, is moved from its place with the help of a sufficiently long and strong stick - a lever.

The lever is a rigid body capable of rotating around a fixed support. The lever has two arms. The shoulder is the distance from the fulcrum to the point of application of force. A crowbar, a board, and the like can be used as a lever. There are patterns:(See slide 1).

1) the longer the arm, the less force is needed to lift the same load;

2) the longer the arm, the longer it travels;

3) how many times the lever arm is, how many times less the load must be to maintain balance.

I managed to formulate these regularities in a language understandable to elementary school students, because we are not yet familiar with inverse proportionality and the properties of proportions. And to visually verify the validity of the laws, a self-made laboratory installation - a lever made from the Lego constructor - helped.

There are two types of levers.

For a lever of the 1st kind, the fixed point of support O is located between the lines of action of the applied forces, and for a lever of the 2nd kind, it is located on one side of them.(See slide 1).

Using leverage allows you to get a gain in strength. To calculate the gain in strength obtained with the help of a lever, one should know the rule discovered by Archimedes back in the 3rd century BC. BC e.

So,in order to balance a smaller force with a larger force, it is necessary that its shoulder exceed the shoulder of a larger force .

Since Archimedes established the rule of the lever, it has existed in its original form for almost 1900 years.

Thus, in most cases, the leverage is used in order to obtain a gain in strength, i.e. increase the force acting on the body several times.

2. 4. Varieties of the lever

The varieties of the lever are two simple mechanisms: block and gate.(See slide 1).

Block is a device in the form of a wheel with a groove through which a rope, cable or chain is passed.

There are two main types of blocks - movable and fixed.(See slide 1).

At the fixed block, the axis is fixed and when lifting loads it does not rise or fall, and at the movable block, the axis moves along with the load. A fixed block does not give a gain in strength. It is used to change the direction of a force. So, for example, applying a downward force to a rope thrown over such a block, we make the load rise up.

The situation is different with the moving block. This block allows a small force to balance a force 2 times greater.

In practice, a combination of a movable block with a fixed one is often used. This allows you to change the direction of the force action with a simultaneous double gain in strength.

To obtain a greater gain in strength, a lifting mechanism is used, calledchain hoist . Greek word"Polyspast" is formed from two roots: "poly" - a lot and "spao" - I pull, so that in general it turns out "multi-thrust".(See slide 1).

The chain hoist is a combination of two clips, one of which consists of three fixed blocks, and the other of three movable blocks. Since each of the moving blocks doubles the traction force, in general, the chain hoist gives a sixfold gain in strength.

The gate consists of a cylinder (drum) and a handle attached to it. This simple mechanism was invented in ancient times. Most often it was used to raise water from wells.(See slide 1).

A more advanced mechanism is a winch. It is a combination of a gate with two gear wheels of different diameters. The winch can be thought of as a combination of two winches.(See slide 1).

Centuries-old practice has proved that none of the mechanisms gives a gain in work. They are used in order to win in strength or path, depending on the working conditions. Already ancient scientists knew the rule: how many times we win in strength, how many times we lose in distance. This rule has been called the "golden rule" of mechanics. Its author is the ancient Greek scientist Heron of Alexandria, who lived inIcentury AD(See slide 1).

III . Practical part.

Having studied theoretical material about the history of the lever, about its discoverer, about the principle of operation and varieties, I decided to conduct research.

3.1. Levers in technology and in everyday life.

In our modern world levers are widely used both in nature and in man-made world created by man. Virtually any mechanism that transforms mechanical movement, in one form or another uses leverage.

Levers meet in different parts human and animal bodies. These are, for example, limbs, jaws. Many levers can be seen in the body of insects and birds.

Levers are also common in everyday life, this is a faucet, and a door, and various kitchen appliances.(See slide 1).

The lever rule underlies the action of lever balances, various kinds of tools and devices used where gain in strength or distance is required.(See slide 1).

We can observe a gain in strength and distance when working with scissors. Scissors is a lever, the axis of rotation of which passes through the screw connecting the two halves of the scissors. Depending on the purpose of the scissors, their device is different. Paper scissors have long blades and handles that are almost the same length.Cutting paper does not require much force, and long blade easier to cut in a straight line. In this case, we have a gain in distance. Cutting scissors sheet metal have handles much longer than the blades, since the resistance force of the metal is great and to balance it, the shoulder of the acting force has to be significantly increased. The difference between the length of the handles and the distance of the cutting part and the axis of rotation in wire cutters is even greater. It is obvious that in these cases there is a gain in strength. (See slide 1).

Levers are also used in other tools - these are the handles of vices and workbenches, the levers of machine tools, carpentry tools, lifeguard tools, etc.(See slide 1).

Of course, various types of levers are common in technology. Most simple examples their applications aregear shift lever in a car, car or tractor pedals, bicycle handbrake.(See slide 1).

Even the handle of a sewing machine and the keys of a piano are also levers.(See slide 1).

We all love sports! And if we look closely, we will see that leverage is also applied in this area.Pole high jumpvery clear example, With the help of a lever about three meters long and the right application of effort, the athlete takes off to a dizzying height of up to six meters. In addition, many sports equipment is equipped with levers.(See slide 1).

For any construction site excavators and tower cranes work - this is a combination of levers, blocks, gates. Depending on the "specialty" cranes have various designs and characteristics.(See slide 1).

Leverage has been widely used in agriculture– tractors, combines, seeders and other mechanisms.(See slide 1).

So,in most cases, simple mechanisms (Greek "mekhane" - a machine, a tool) are used in order to gain a gain in strength.

3.2. Laboratory work

Equipment : lever on a tripod, a set of weights, a ruler.

Target : find out the equilibrium conditions of the lever.

Working process.

1. By rotating the nuts on the ends of the lever, I balanced it so that it is located horizontally.

2. Suspended three weights to the left shoulder of the lever at a distance of 7 cm from the axis of rotation.

3. By trial, I determined the place on the right shoulder of the lever, from which one weight should be hung in order to balance the previous three. I measured the distance from this place to the axis of rotation.

4. Assuming that each load weighs 1 N, I filled out the table.

5. Concluded the validity of the lever balance rule.

(See slide 1).

l2 : l1

7 cm

21 cm

10 cm

20 cm

9 cm

18 cm

3.3 Experiments at home.

Using the book of Ya.I. Perelman " Entertaining physics"and the materials of the Internet sites" Cool! Physics "and" Physics around us "conducted entertaining experimentswith levers.

1. Cars. (See slide 1).

I took a big one and a small one toy cars. I put them on the ends of the ruler, laid in the middle on a round pencil. The big machine pulled over, tk. she is heavier. If you move the pencil closer to the big typewriter, they will balance. When I moved the pencil even closer to the big typewriter, the small one outweighed it.

2. How much strength is in the fingers?

I took two round toothpicks. Put one toothpick in the middle middle finger(closer to the nail), and at the ends - index and nameless. Tried to break a toothpick by pressing on it with the index and ring fingers. He moved the toothpick to the middle of his finger. Tried to break the toothpick again. When the toothpick was at the fingertips, it was almost impossible to break it (the fingers served as a lever of the second kind, similar to nutcrackers). The fulcrum is where the fingers begin.The further the toothpick is from the fulcrum, the more force must be applied. ?????

3. Polyspast.

He tied a rope to the handle of a ski pole. I placed both sticks at a distance of 50 cm from each other and wrapped the rope around their handles three times. Pulled the free end of the rope while my assistants tried to sever the sticks. Even though my friends are trying to spread the sticks apart, I alone can move them together. (The sticks and rope behave like a chain hoist - my force is multiplied by the rope wrapped around the handles of the sticks, so I gain almost five times the strength compared to my assistants.

4. Lever. (See slide 1).

An ordinary stick has become a lever for a person - the simplest mechanism. On an ordinary stick it is very convenient for two to carry the load. Using it, you can easily lift and move weights.

Experience 1. I took a not very long stick, put it under the handle of the suitcase and, having invited a friend to help, we lifted the suitcase together. If the suitcase is exactly in the middle, then each of us is loaded equally. When we moved the suitcase to one of the ends of the stick, everything changed. The load has become lighter for those who hold the long end. The shoulders of the lever have changed, and the ratio of forces that hold the load in the raised position has also changed. The hands of each of us are the support of the lever, and if the distance to the load is less, then the load on this fulcrum will be greater.

Experience 2 . I took a small stick and drove a nail into the side near one of its ends. I put an iron on this end (a nail is needed so that the iron does not slip on the floor) and put the lever on the back of the chair. Holding the lever by the free end, he moved it, now bringing the fulcrum closer to the load, then moving away from it. I found that the greater the distance from the hand to the fulcrum, the easier it is to hold the load. I got the same result when I moved my hand along the lever to the fulcrum, leaving the distance from the fulcrum to the load unchanged.

5. I pull out the nail.

Using a hammer, I drove a nail into a piece of wood 2/3 of its length. He tried to pull a nail out of a piece of wood with his hands. I didn't succeed, no matter how hard I tried. Then I took a nail puller and easily pulled out the nail with it. The nail puller in my case acts as a lever,which is a simple apparatus used forovercoming resistance at the second point, by applying force.

3.4. Manufacture of devices and models operating on the principle of a lever.

Applying the knowledge gained from studying the lever, I made the following devices and models with the help of my father.

1. Winch with your own hands. (See slide 1).

From bad road no one is insured, and if your car is stuck in the mud, only a winch will help save it. Is it worth it to spend a huge amount of money on an expensive thing and buy it in a store when you can make a winch with your own hands.

We needed:

An axis for rotation and 2 suitable tubes of larger and smaller diameters;

Strong rope;

Working process:

Our handmade winch works on the principle of a lever. For the base homemade winch can serve as a piece of pipe. To put the pipe into operation, it must be put on the axis and secured with a cable. The cable loop must be wound several times around the pipe and put on any handle.

When the handle is turned, the pipe will rotate along the axis, and the cable will be wound around it. Such a winch is useful not only to pull the car out of the mud, but also to move various loads, for example, in the country.

2. Polyspast. (See slide 1).

I took a strong nylon cord, 2 separate blocks, a load. I assembled a combination of 1 movable and 1 fixed block and fixed them.Now I can easily lift loads that I could not simply hold in my hand without a chain hoist.

Having conducted an experiment with a dynamometer, I was convinced that the chain hoist gives a double gain in strength!

IV . Conclusion.

As a result of the work carried out, I was convinced that next rule- how many times we win in strength, how many times we lose in distance.

I learned about the history of the lever, about its discoverer, about the principle of operation and varieties.

Levers different types meet in everyday life at every step:

A wheelbarrow is easier to carry if it has long handles;

It is easier to pull out a nail if the nail puller is longer;

It is much easier to tighten the nut with a wrench with a long handle.

You should never forget the "golden rule" of mechanics, which is simplified as follows: gain in strength - loss in transit. Sometimes it is worth sacrificing a shorter path in order to win in strength. The work will still be the same, but it will be easier to do it because the increase in the path corresponds to the increase in time. And for a longer period of time, work is easier to do - this is clear to everyone.

When designing machines, it also happens the other way around, when you have to sacrifice strength in order to win on the road, to win in time.

While working on the topic, I own experience I became convinced that the lever and its varieties really give a person a gain in strength or distance, or are used for convenience. Thus, he confirmed his hypothesis that not every strong man is necessarily strong. Now I am getting stronger not only through daily physical training, but also by applying the new knowledge I have gained. The title of my work should never be pronounced with an affirmative intonation. On the contrary, if there is intelligence, there will be strength. The materials of my research will undoubtedly be useful in the lessons of the surrounding world in primary school, and maybe at physics lessons in the 7th grade.

In conclusion, I would like to recall the words of the Hedgehog from Vladimir Suteev's wonderful fairy tale "The lifesaver": "You can always find a stick, but here's a lifesaver - and here's the lifesaver!".

Literature

1. Balashov M.M. Physics. – M.: Enlightenment, 1994.

2. Katz Ts.B. Biophysics at physics lessons. – M.: Enlightenment, 1988.

3. Perelman Ya.I. Entertaining physics. Book 1. - M .: Nauka, 1979.

4. Physics. Grade 7 / Gromov S.V., Rodina N.A. – M.: Enlightenment, 2000.

5. Physics. Grade 7 / Peryshkin A.V., Rodina N.A. – M.: Drofa, 2003.

6. Encyclopedia for children. T. 14 - Technique. – M.: Avasta+, 2000.

7. I know the world. Children's encyclopedia - The world of beauty. – M.: Astrel, 2004.

Appendix

Photo report

Laboratory work"Clarification of the conditions for the equilibrium of the lever"

My experiments http://vse-svoimiruchkami.ru/glavnaya/ )

Making a chain hoist

Interscholastic Conference City Tour

"First Steps in Science".

Job title“There is power! Mind is not necessary?

Student(s) (surname, full name)Abramov Danila

MBOU SOSH ________ 32__ class ___________ 4 B

Work managerZibert Galina Ivanovna

Type of work (project / abstract / research)study

Criteria for evaluating work

1) Compliance with the requirements for the design of work.All requirements met .

2) The volume of the studied material:search for information in the literature and the Internet, observation, description and measurement, experimental work, modeling.

3) Cognitive value, relevance, practical and theoretical significance of the studied material.In the work, the origin and types of levers are studied, experiments with a lever are carried out, and devices operating on the principle of a lever are modeled.

4) Problem, hypothesis, goal, tasks of the work.Hypothesis: Most likely, there are mechanisms that help a person become stronger. Purpose: to find out the principle of operation of the simplest mechanisms. Objectives: to conduct experiments to identify the properties of the lever and the principle of its operation.

5) Research skills (arguments, conclusions; literacy, logical presentation of the material, adherence to the scientific style of presentation)The work was done correctly scientific style presentations, conclusions are drawn for each experience and for the work as a whole.

Reviewer's signature (signature transcript)

Uyukina Ludmila Grigorievna

Levers in technology, everyday life and nature

LEVER - the simplest mechanism that allows a smaller force to balance a large one; is a rigid body rotating around a fixed support. lever technique use nature

The lever is used to get more force on the short arm with less force on the long arm (or to get more movement on the long arm with less movement on the short arm). By making the lever arm long enough, theoretically, any effort can be developed.

In many cases, in everyday life, we use such simple mechanisms as:

*inclined plane,
*using blocks,
* also use wedge, screw.

Tools such as a hoe or a paddle were used to reduce the amount of force a person had to exert. Steelyard, which allowed to change the shoulder of the application of force, which made the use of scales more convenient. An example of a compound lever used in everyday life can be found in nail clippers. Cranes, motors, pliers, scissors, and thousands of other machines and tools use levers in their construction.

Levers are also common in everyday life. It would be much more difficult for you to open a tightly screwed faucet if it did not have a 3-5 cm handle, which is a small but very effective lever. The same applies to a wrench, which you use to unscrew or tighten a bolt or nut. The longer the wrench, the easier it will be for you to unscrew this nut, or vice versa, the tighter you can tighten it. When working with especially large and heavy bolts and nuts, for example, when repairing various mechanisms, cars, machine tools, they use spanners with a handle up to a meter.

Another striking example of a lever in everyday life is the most ordinary door. Try to open the door by pushing it near the hinges. The door will give in very hard. But the farther from door hinges the point of application of force will be located, the easier it will be for you to open the door.

Pole vault is also a very good example. With the help of a lever about three meters long (the length of a pole for high jumps is about five meters, therefore, the long arm of the lever, starting at the bend of the pole at the time of the jump, is about three meters) and the correct application of effort, the athlete takes off to a dizzying height up to six meters.

An example is scissors, wire cutters, scissors for cutting metal. Many machines have levers of various kinds: the handle of a sewing machine, the pedals or handbrake of a bicycle, the keys of a piano, are all examples of levers. Libra is also an example of a lever.

Since ancient times, simple mechanisms have often been used in complex, in a variety of combinations.

The combined mechanism consists of two or more simple. This is not necessarily a complex device; many fairly simple mechanisms can also be considered combined.

For example, in a meat grinder there is a gate (handle), a screw (pushing meat) and a wedge (knife-cutter). Arrows wrist watch are rotated by a system of gears of different diameters meshing with each other. One of the most famous simple combined mechanisms is a jack. The jack is a combination of screw and collar.

In the skeleton of animals and humans, all bones that have some freedom of movement are levers. For example, in humans - the bones of the arms and legs, lower jaw, skull, fingers. In cats, movable claws are levers; many fish have spines on the dorsal fin; in arthropods, most segments of their external skeleton; bivalve mollusks have shell valves. Skeletal linkages are primarily designed to gain speed with a loss in strength. Especially large gains in speed are obtained in insects.

Interesting linkage mechanisms can be found in some flowers (such as sage stamens) and also in some drop-down fruits.

For example, the skeleton and musculoskeletal system of a person or any animal consists of tens and hundreds of levers. Let's take a look at the elbow joint. The radius and humerus are connected together by cartilage, and the muscles of the biceps and triceps are also attached to them. So we get the simplest lever mechanism.

If you hold a 3 kg dumbbell in your hand, how much effort does your muscle develop? The junction of the bone and muscle divides the bone in a ratio of 1 to 8, therefore, the muscle develops a force of 24 kg! It turns out that we are stronger than ourselves. But the lever system of our skeleton does not allow us to fully use our strength.

A good example of the better application of leverage to the musculoskeletal system is the reverse hind knee in many animals (all kinds of cats, horses, etc.).

Their bones are longer than ours, and their special structure hind legs allows them to use their muscle strength much more efficiently. Yes, of course, their muscles are much stronger than ours, but their weight is an order of magnitude greater.

The average horse weighs about 450 kg, and at the same time can easily jump to a height of about two meters. To perform such a jump, you and I need to be masters of sports in high jumps, although we weigh 8-9 times less than a horse.

Since we remembered the high jump, consider the options for using the lever, which were invented by man. Pole high jump very clear example.

With the help of a lever about three meters long (the length of the pole for high jumps is about five meters, therefore, the long arm of the lever, starting at the bend of the pole at the time of the jump, is about three meters) and the correct application of effort, the athlete takes off to a dizzying height of up to six meters.

Lever in everyday life

Levers are also common in everyday life. It would be much more difficult for you to open a tightly screwed faucet if it did not have a 3-5 cm handle, which is a small but very effective lever.

The same applies to a wrench, which you use to unscrew or tighten a bolt or nut. The longer the wrench, the easier it will be for you to unscrew this nut, or vice versa, the tighter you can tighten it.

When working with especially large and heavy bolts and nuts, for example, when repairing various mechanisms, cars, machine tools, wrenches with a handle up to a meter are used.

Another striking example of leverage in everyday life is the most common door. Try to open the door by pushing it near the hinges. The door will give in very hard. But the farther from the door hinges the point of application of force is located, the easier it will be for you to open the door.

Scissors.

Here is one example of simple scissor mechanisms whose axis of rotation passes through the screw connecting the two halves of the scissors. Using blocks on construction sites to lift loads.

A gate or lever is used to raise water from a well. A wedge driven into a log bursts it with more force than a hammer hits a wedge.

Lever (used in loom, steam engine and in internal combustion engines), screw (used in the form of a drill), lever (used in the form of a nail puller), pistons (changes in gas, vapor or liquid pressure into mechanical work).

Levers in nature, technology and everyday life.

Give me a point of support and I will turn Earth!

Archimedes.

Lesson goals.

Educational.

1. To form the ability to apply the acquired knowledge to explain the actions of simple mechanisms.

2. Deepen knowledge about the use of levers in technology, everyday life and nature

3. Introduce the concept of a block, its types.

Developing.

1. Development cognitive interests, communicative qualities.

2. Development of technical thinking.

3. Development of skills and abilities of independent work.

Educational.

1. To cultivate responsibility, discipline, conscientious attitude to the work performed.

2. To instill the skills of cooperation, the ability to work in a team.

Lesson type : combined (assimilation of knowledge based on existing)

Teaching methods : practical, visual, research, search.

Intersubject communications Keywords: mathematics, biology, technology.

Equipment: presentation, scissors, wire cutters, tongs. Instructions for practical work.

During the classes:

1. Org. moment. (opening remarks)

2 . Repetition of what was learned earlier. (puzzles)

3 . Study of new topic

Student 1. Levers in technology

Naturally, levers are also ubiquitous in technology. The most obvious example is the gear lever in a car. The short lever arm is the part that you see in the cabin.

The long arm of the lever is hidden under the bottom of the car, and is about twice as long as the short one. When you shift the lever from one position to another, a long arm in the gearbox switches the corresponding mechanisms.

Here you can also very clearly see how the length of the lever arm, the range of its travel and the force required to shift it correlate with each other.

For example, in sports cars, for faster gear changes, the lever is usually set short, and its range is also made short.

However, in this case, the driver needs to make more effort to change gear. On the contrary, in heavy vehicles, where the mechanisms themselves are heavier, the lever is made longer, and its range of travel is also longer than in a passenger car.

Thus, we can be convinced that the lever mechanism is very widespread both in nature and in our daily life, and in various mechanisms.

Slide task.

Student 2 . Lever in everyday life.

Levers are also common in everyday life. It would be much more difficult for you to open a tightly screwed faucet if it did not have a 3-5 cm handle, which is a small but very effective lever.

When working with especially large and heavy bolts and nuts, for example, when repairing various mechanisms, cars, machine tools, wrenches with a handle up to a meter are used.

Student 3 . The human body as a lever

A good example of the better application of leverage to the musculoskeletal system is the reverse hind knee in many animals (all kinds of cats, horses, etc.).

Their bones are longer than ours, and the special structure of their hind legs allows them to use the strength of their muscles much more efficiently. Yes, of course, their muscles are much stronger than ours, but their weight is an order of magnitude greater.

An average horse weighs about 450 kg, and at the same time can easily jump to a height of about two meters. To perform such a jump, you and I need to be masters of sports in high jumps, although we weigh 8-9 times less than a horse.

Since we remembered the high jump, consider the options for using the lever, which were invented by man. The pole vault is a very good example.

Pupil 4 . Plants. Many levers can be indicated in the body of insects, birds, in the structure of plants. For example, the stamens of a sage flower are a kind of leverage. Two arms extend from the axis of the stamens: long and short. A pollen sac hangs at the end of a long arm, curved like a yoke, and the short arm is flattened. It closes the entrance to the depth of the flower, where the nectar is located. The bumblebee, trying to reach the nectar, always touches the short shoulder. At the same time, the long arm descends, showering the back of the bumblebee with pollen. And the bumblebee flies further, touches the stigma of the pistil of the new flower and pollinates it.

Student 5. Conclusion . Even before our era, people began to use leverage in the construction business, for example, when building the pyramids in Egypt. The lever allows you to get a gain in strength, however, is such a gain given “for free”? When using a lever, its longer end travels a greater distance. Thus, having received a gain in strength, we get a loss in distance. This means that by lifting a large load with a small force, we are forced to make a greater displacement.

4. Physical pause. Riddles.

Practical work .

Purpose: to analyze information about the use of levers in everyday life.

Task for the group1.

Determine the force of pressure of scissors on a sheet of paper using scissors, a dynamometer. Instructions for completing the task are attached.

Fill in the table.

applied force

F1,N

Shoulder l1, cm

Shoulder

l2 cm

The pressure force of the scissors,

F2, N

Equilibrium rule

F1 = l2

F2 l1

Moment of forces

M 1= M2

Win in force:

Conclusion:

INSTRUCTION.

1. Take scissors.

2. Using a ruler, measure the distance l1, cm from the center of the scissors (stud) to the center of the scissor rings. Record the result in a table.

3. Take a sheet of paper, make an incision and use a ruler to measure the distance from the center of the scissors (nail) to the sheet of paper (see figure). The result obtained l2, see write down in the table.

4. Take a dynamometer. Scissors with a sheet of paper lead in working position(see figure), hook the dynamometer hook on the ring of the scissors and pull until the scissors cut the sheet of paper. And at this moment, record the readings of the dynamometer, F1 Record the data in the table.

5. Using the formula for the lever balance rule, calculate the pressure force of the scissors F2 on the sheet of paper.

6. Check whether the rule of balance of the lever and the rule of moments are observed. Record the results in the table.

Practical work.

Purpose: to analyze information on the use of leverage in nature

Task for the group2.

Calculate the strength of the muscles of your hand when lifting the load and its

fixation. Instructions for completing the task are attached. .

Fill in the table.

load pressure force,

F2, H

shoulder l2 , cm

Shoulder

l1 , cm

arm muscle strength

F 1, H

Equilibrium rule

F 1 = l 2

F2 l1

Moment of forces

M1 = M2

Win in force:

Conclusion:

INSTRUCTION.

1. Take a set of weights in your hand.

2. Using a ruler, measure the distance l2, cm from the axis of rotation of the arm (elbow) to the place where the load is fixed. Record the result in a table.

3. Calculate the pressure force of the load F2, knowing that there are 3 loads in the set, and the pressure force of one load is 1 N. Write the data in the table.

4. Using a ruler, measure the distance l1, cm from the axis of rotation of the arm (elbow) to the muscle of the arm, see figure. Record the result in a table.

5. Using the formula for the balance rule of the lever, calculate the strength of the muscles of the arm F1 when lifting the load.

6. Check whether the rule of balance of the lever and the rule of moments are observed. Record the results in a table.

7. Determine the gain in strength.

8. Draw a conclusion using the data in paragraphs 6 and 7.

5. Reflection. Draw a smiley face in the margins, smiling if you liked the lesson, serious if something was left incomprehensible and dull if you didn’t like the lesson.

6. The results of the lesson: grading.

7. Homework.

LEVERS In technique. Wedge and screw - a kind of inclined plane. The wedge is intended for splitting of strong objects, for example, logs. It is also driven into the gaps between the parts in order to create a greater pressure force of one part on another and thereby increase the static friction force between them, which will ensure their reliable adhesion. With the enormous forces applied to the wedge, it must be very strong, made of the hardest material. The "piercing tools" of many animals and plants - claws, horns, teeth and thorns - are shaped like a wedge (a modified inclined plane); the pointed shape of the head of fast-moving fish is similar to a wedge. Many of these wedges have very smooth hard surfaces, which achieves their great sharpness.

Slide 9 from the presentation "Leverage in nature and technology" to physics lessons on the topic "Lever"

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Lever arm

"Levers in everyday life" - simple mechanisms. Levers in everyday life. Varieties of the lever: block and gate. Inclined plane. Lever block gate. Tilting plane wedge screw. What can a person use to do work? Lever balance. mechanical work. Levers in technology and everyday life: a press with a lever. During the construction of the pyramids in ancient Egypt.

"Levers" - Scissors for cutting metal. Axis of rotation. Levers in everyday life, technology and nature. In which case is it easier to carry the load? Gate. Support point. Wheelbarrow.

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Where levers are used in everyday life technology. Research paper in physics about the lever

Lever arm

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