Examples of levers in physics technology. Simple mechanisms in living nature

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Human physical capabilities are limited, therefore, since ancient times, people have often used devices that can convert human strength into much greater strength. The lever is one of the most common and simple types of mechanisms in the world, present both in nature and in the man-made world created by man. Thus, this confirms the choice of topic for my project “Levers in everyday life and wildlife.” Project goal: Learn to use simple mechanisms (levers) as devices used to convert force. Objectives: consider various types of simple mechanisms as devices used to convert force; deepen knowledge about the use of levers in everyday life and wildlife; make a presentation. Levers in everyday life and wildlife

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Levers in everyday life and living nature Simple mechanisms are devices (devices) that allow you to convert force into significantly greater force. Simple mechanisms Lever Inclined plane (block, gate, crowbar) (wedge, screw) Lever is a solid body that can rotate around a fixed support. The lever began to be used by people in ancient times. With its help, it was possible to lift heavy stone slabs during the construction of pyramids in Ancient Egypt.

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Levers in everyday life and wildlife We gain in strength when working with scissors. Scissors are a lever whose axis of rotation passes through a screw connecting both halves of the scissors. Depending on the purpose of the scissors, their design varies. stationery for cutting sheet metal tailor's cutters The difference between the length of the handles and the distance of the cutting part from the axis of rotation in the cutters is even greater. They are designed for cutting wire and not very thick nails. manicure

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Levers in everyday life and wildlife Tower cranes operate on any construction site - this is a combination of levers, blocks, and gates. Depending on the “specialty”, cranes have different designs and characteristics. construction gantry floating crane

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Levers in everyday life and wildlife The action of lever scales is based on the principle of leverage. All scales shown in the figures act as an equal-arm lever, i.e. the weight of the load on one bowl is equal to the weight of the weights on the other bowl.

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Levers in everyday life and in wildlife Many machines have different types of levers. Examples include the handle of a sewing machine, a meat grinder, bicycle pedals or handbrake, car and tractor pedals, piano keys - all these are examples of levers used in these machines and tools.

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Levers in everyday life and wildlife Levers are also found in different parts of the body of animals and humans. Many levers can be identified in the body of insects, birds, and in the structure of plants. In the animal skeleton, all the bones that have some freedom of movement are levers: the bones of the legs and arms, the skull, the lower jaw. The levers of many fish are the spines of the dorsal fin. Levers in arthropods are most of the segments of their exoskeleton. The levers of bivalve mollusks are the shell valves. Skeletal lever mechanisms are primarily designed to gain speed while losing strength. The speed gain is especially great for insects.

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Levers in everyday life and wildlife Let us remember the Russian folk tale “Turnip”. Grandfather planted a turnip, and the turnip grew big and big. Grandfather tried to pull the turnip, but he couldn’t pull it out. The grandfather called the grandmother, granddaughter, Bug, cat, mouse and pulled out the turnip. Or you could have done it yourself by taking a shovel, prying up a turnip and that’s it. A shovel is a lever that gives you a gain in strength; you can grab it by the larger shoulder using less force.

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Levers in everyday life and living nature The Russian people did not understand scientific intricacies, but they were savvy. Let us remember Lev Nikolayevich Tolstoy and his story “How a man removed a stone”... In a square in one city there was a huge stone. The stone took up a lot of space and interfered with driving around the city. Engineers were called in, but they offered to remove the stone for a lot of money. And one man said: “And I’ll remove the stone and take a hundred rubles for it!” They asked him how he would do it. And he said: “I will dig a large hole next to the stone; I will scatter the earth from the hole over the area, throw the stone into the hole and level the ground.” Why don't you like physics? The man applied the “golden rule” of mechanics: The number of times we win in strength, the same number of times we lose in distance.

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Levers in everyday life and wildlife Thus, we can draw conclusions: A lever is one of the simple mechanisms with which you can win in strength or movement. These properties of the lever determine their widespread use in everyday life. We use mechanisms with levers, invented hundreds of years ago and in our time, which are updated with new inventions. People use levers without thinking about how they work. Levers are our helpers in everyday life, and nature takes care of itself. But the main thing I understood: Physics... what a “capacity” of a word! Physics is not just sound for us. Physics is the support and basis of all sciences without exception!

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Levers in technology, everyday life and nature

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

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

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

*inclined plane,
*using blocks,
*a wedge or a screw is also used.

Tools such as a hoe or paddle were used to reduce the force a person needed to exert. Steelyard, which made it possible to change the leverage 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, engines, pliers, scissors, and thousands of other mechanisms and tools use levers in their design.

Levers are also common in everyday life. It would be much more difficult for you to open a tightly screwed water tap if it did not have a 3-5 cm handle, which is a small but very effective lever. The same applies to a wrench that you use to loosen 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 particularly large and heavy bolts and nuts, for example, when repairing various mechanisms, cars, machine tools, use wrenches with a handle up to a meter.

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

Pole high jumping is also a very clear example. Using a lever about three meters long (the length of a high jump pole is about five meters, therefore, the long arm of the lever, starting at the bend of the pole at the moment of the jump, is about three meters) and the correct application of force, the athlete soars to a dizzying height of up to six meters.

Examples include scissors, wire cutters, and metal cutting shears. Many machines have different types of levers: the handle of a sewing machine, the pedals or handbrake of a bicycle, the keys of a piano are all examples of levers. The scale is also an example of a lever.

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

A combined mechanism consists of two or more simple ones. It 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 the meat) and a wedge (cutting knife). The hands of a wristwatch are turned by a system of gear wheels of different diameters that mesh with each other. One of the most famous simple combined mechanisms is the jack. The jack is a combination of a screw and a gate.

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, levers are movable claws; in many fish there are spines on the dorsal fin; in arthropods - most segments of their exoskeleton; in bivalves, shell valves. Skeletal lever mechanisms are primarily designed to gain speed while losing strength. Particularly large gains in speed are obtained in insects.

Interesting lever mechanisms can be found in some flowers (such as sage stamens) and also in some dehiscent 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 biceps and triceps muscles are also attached to them. So we get the simplest lever mechanism.

If you hold a 3 kg dumbbell in your hand, how much force does your muscle develop? The junction of bone and muscle is divided by 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 clear example of a more successful application of the advantages of leverage in the musculoskeletal system of the body is the reverse hind knees in many animals (all types of cats, horses, etc.).

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

The average horse weighs about 450 kg, and can easily jump to a height of about two meters. You and I, in order to perform such a jump, need to be masters of sports in high jumping, although we weigh 8-9 times less than a horse.

Since we remembered about high jumps, let's consider the options for using a lever that were invented by man. High vault a very clear 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 moment of the jump, is about three meters) and the correct application of force, the athlete soars 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 water tap if it did not have a 3-5 cm handle, which is a small but very effective lever.

The same applies to a wrench that you use to loosen 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 particularly large and heavy bolts and nuts, for example, when repairing various mechanisms, cars, machine tools, use wrenches with a handle up to a meter.

Scissors.

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

A winch or lever is used to lift water from a well. A wedge driven into a log pushes it apart with greater force than a hammer hits the wedge.

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

Levers in technology, everyday life and nature.

The rule of leverage (or the rule of moments) underlies the action of various kinds of tools and devices used in technology and everyday life where a gain in strength or travel is required.

We have a gain in strength when working with scissors. Scissors - this is a lever(Figure 1), the axis of rotation of which occurs through a screw connecting both halves of the scissors. The acting force F1 is the muscular force of the hand of the person gripping the scissors. Reacting force F2 is the resistance force of the material being cut with scissors. Depending on the purpose of the scissors, their design varies. Office scissors, designed for cutting paper, have long blades and handles that are almost the same length. Cutting paper does not require much force, and a long blade makes it easier to cut in a straight line.

Sheet metal shears(Figure 2) have handles much longer than the blades, since the resistance force of the metal is large and to balance it, the arm 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 is even greater wire cutters(Figure 3), designed for cutting wire.

Many machines have different types of levers. The handle of a sewing machine, the pedals or handbrake of a bicycle, the pedals of a car and tractor, and the keys of a piano are all examples of levers used in these machines and tools.

Examples of the use of levers are the handles of vices and workbenches, the lever of a drilling machine, etc.

The action of lever scales is based on the principle of the lever (Figure 4). The training scales shown in Figure 5, which you already know from the “Mass” paragraph, act as equal-arm lever. In decimal scales (Figure 6), the arm from which the cup with weights is suspended is 10 times longer than the arm carrying the load. This makes weighing large loads much easier. When weighing a load on a decimal scale, you should multiply the mass of the weights by 10.

The device of scales for weighing freight cars of cars is also based on the rule of leverage.

Levers are also found in different parts of the body of animals and humans. These are, for example, arms, legs, jaws. Many levers can be found in the body of insects (by reading a book about insects and the structure of their bodies), birds, and in the structure of plants.

Application of the law of equilibrium of a lever to a block.

Block It is a wheel with a groove, mounted in a holder. A rope, cable or chain is passed through the block groove.

Fixed block This is a block whose axis is fixed and does not rise or fall when lifting loads (Figure 7).

A fixed block can be considered as an equal-arm lever, in which the arms of forces are equal to the radius of the wheel (Fig): OA = OB = r. Such a block does not provide a gain in strength. (F1 = F2), but allows you to change the direction of the force.

Movable block - this is a block. the axis of which rises and falls along with the load (Figure 8). The figure shows the lever corresponding to it: O is the fulcrum of the lever, OA is the arm of the force P and OB is the arm of the force F. Since the arm OB is 2 times larger than the arm OA, the force F is 2 times less than the force P:

F = P/2.

Thus, the movable block gives a 2-fold gain in strength.

This can be proven using the concept of moment of force. When the block is in equilibrium, the moments of force F and P are equal to each other. But the arm of force F is 2 times greater than the arm of force P, then the force F itself is 2 times less than the force P.

Usually in practice a combination of a fixed block and a movable one is used (Figure 9). The fixed block is used for convenience only. It does not give a gain in strength, but it changes the direction of the force, for example, it allows you to lift a load while standing on the ground.

“I could turn the Earth with a lever, just give me a fulcrum”

Archimedes

Lever- one of the most common and simple types of mechanisms in the world, present both in nature and in the man-made world.A lever is a rigid body that can rotate around a certain axis. A lever is not necessarily a long and thin object.

The human body is like a lever

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 limbs, the lower jaw, the skull, the phalanges of the fingers.

Let's take a look at the elbow joint. The radius and humerus are connected together by cartilage, and the biceps and triceps muscles are also attached to them. So we get the simplest lever mechanism.

A clear example of a more successful application of the advantages of leverage in the musculoskeletal system of the body is the reverse hind knees in many animals (all types of cats, horses, etc.).

Since we remembered about high jumps, let's consider the options for using the lever that were invented by man. Pole high jumping is a very clear example.

Using a lever about three meters long (the pole for high jumps is about five meters long, therefore, the long arm of the lever, starting at the bend of the pole at the moment of the jump, is about three meters) and the correct application of force, the athlete soars to a dizzying height of up to six meters.

Take a pen, write something or draw something and watch the pen and the movement of your fingers. You will soon discover that a handle is a lever. Find your fulcrum, evaluate your shoulders and make sure that in this case you lose in strength, but gain in speed and distance. Actually, when writing, the friction force of the stylus on the paper is small, so the finger muscles do not strain too much. But there are types of work when the fingers must work at full capacity, overcoming significant forces, and at the same time make movements of exceptional precision: the fingers of a surgeon, a musician.

Lever in everyday life

Levers are also common in everyday life. It would be much more difficult for you to open a tightly screwed water tap if it did not have a 4-6 cm handle, which is a small but very effective lever.

The same applies to a wrench that you use to loosen 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 particularly large and heavy bolts and nuts, for example, when repairing various mechanisms, cars, machine tools, use wrenches with a handle up to a meter.

In plants, lever elements are less common, which is explained by the low mobility of the plant organism. A typical lever is a tree trunk and roots. The roots of a pine or oak deep into the ground offer enormous resistance, so pines and oaks almost never get uprooted. On the contrary, spruce trees, which often have a superficial root system, overturn very easily.

The “piercing tools” of many animals and plants - claws, horns, teeth and spines - are shaped like a wedge (a modified inclined plane); The pointed shape of the head of fast-moving fish is also similar to the wedge. Many of these wedges have very smooth hard surfaces, which gives them great sharpness.

Levers in technology

Naturally, levers are also ubiquitous in technology.

The simple “lever” mechanism has two varieties: block and gate.

With the help of a lever, a small force can balance a large force. Consider, for example, lifting a bucket from a well. The lever is a well gate - a log with a curved handle or wheel attached to it.

The axis of rotation of the gate passes through the log. The lesser force is the force of the person's hand, and the greater force is the force with which the bucket and the hanging part of the chain pulls down

Even before our era, people began to use levers in construction. For example, in the picture you see the use of a lever when constructing a building. We already know that levers, blocks and presses allow you to gain strength. However, is such a gain given “for free”?

When using a lever, the longer end travels a longer distance. Thus, having gained in strength, we get a loss in distance. This means that when lifting a large load with a small force, we are forced to make a large movement.

The most obvious example is the gearshift lever in a car. The short arm of the lever 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 approximately twice as long as the short one. When you move the lever from one position to another, a long arm in the gearbox shifts the corresponding mechanisms.

For example, in sports cars, to change gears faster, the lever is usually installed short, and its travel range is also short.

However, in this case the driver needs to make more efforts 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.

A simple “inclined plane” mechanism and its two varieties - wedge and screw

An inclined plane is used to move heavy objects to a higher level without directly lifting them. If you need to lift a load to a height, it is always easier to use a gentle lift than a steep one. Moreover, the steeper the slope, the easier it is to complete this work.

A body on an inclined plane is held by a force that... is as many times less in magnitude than the weight of this body as the length of the inclined plane is greater than its height.

A wedge driven into a log acts on it from top to bottom. At the same time, he pushes the resulting halves apart to the left and right. That is, the wedge changes the direction of the force.

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

In addition, the force with which he pushes the halves of the log apart is much greater than the force with which the hammer acts on the wedge. Consequently, the wedge also changes the numerical value of the applied force.

Woodworking and gardening tools were represented by a wedge - a plow, adze, staples, shovel, hoe. The land was cultivated with a plow and harrow. They harvested the crops using rakes, scythes, and sickles.

A screw is a type of inclined plane. With its help you can get a significant gain in strength.

By turning the nut on the bolt, we lift it up an inclined plane and gain strength.

By turning the corkscrew handle clockwise, we cause the corkscrew screw to move downward. A transformation of movement occurs: the rotational movement of the corkscrew leads to its translational movement.

“Levers in nature and technology” - Levers in technology. Lever mechanisms. Archimedes. Levers in living nature. Dorsal fin spines. Levers in arthropods. Levers in wildlife and technology. Movable bones. Levers in bivalves. Lever mechanisms of the skeleton.

“Levers” - Wheelbarrow. Scissors for cutting metal. Support point. In which case is it easier to carry the load? Gate. Rotation axis. Levers in everyday life, technology and nature.

“Leverage” - How else can you use leverage? Cargo. Not all classmates can apply their knowledge about levers. Archimedes, connecting the concepts of force, load and shoulder. Using a computer program, calculating levers is more convenient and faster. The adults explained to me that I used the door as a lever. Lever of the second type. What other properties does a lever have?

“Simple mechanisms - lever” - Title of the list. Lever device. Using leverage. Which lever will be in equilibrium? Mechanisms. Simple mechanisms. Scissors. Lever equilibrium condition. Two types of levers. Consolidation. Shoulder. Why is the door handle not attached to the middle of the door? Adaptations. Lever.

“Block” - Application of the law of lever equilibrium to a block. "Golden rule" of mechanics. When they gain 2 times in strength, they lose 2 times along the way. Equality of work when using a moving block. Fixed block. Combination of blocks. Equality of work when using a lever. There is no gain in work when using leverage.

“Levers in everyday life” - Types of lever: block and gate. Inclined plane wedge screw. Lever balance. Mechanical work. A=fs. Wedge and screw. Gate block lever. Levers in technology and everyday life: single-cup lever scales. Levers in technology and everyday life: a press with a lever. Simple mechanisms. Lever. What can a person use to do work?