What is the knowledge of mechanics in people, and what are the mechanical phenomena around them

The knowledge of mechanics in the human body mainly involves the knowledge of pressure, friction, simple machinery and energy.

1 Knowledge of pressure.

1) Human teeth use the knowledge of pressure. The incisors and canines are sharper, and the crowns of the double cuspids and molars have pointed protrusions, which are all ways to reduce the reception area and increase the pressure to make it easier for people to bite or chew food.

2) The size of people's feet is that the feet of tall people are also larger, so as to ensure that people with different weights walk with the same pressure on the ground.

3) When the person inhales, the chest muscle increases the volume of the chest cavity, the volume of gas of a certain mass in the lungs increases, and the pressure decreases, which is less than the atmospheric pressure outside, and the atmospheric pressure presses the air into the respiratory tract and into the alveoli of the human body; When a person exhales, the chest muscles contract the chest cavity and compress the lungs to reduce its volume, and the volume of a certain mass of gas in the lungs decreases and the pressure increases, which is greater than the atmospheric pressure, thus exhaling carbon dioxide.

4) The flow of blood in the human body is caused by the pressure generated by the contraction of the heart.

2 Knowledge of friction.

1) In the human mouth, the surface of the tongue is rough, and there are also lines on the palate, which increase the friction with the food, which is convenient for agitating the food or sending things into the esophagus.

2) There are special palm prints on the palms and soles of people's feet. When the grip strength is constant, the fingerprints and palm prints on the palm of the hand can increase the friction with the contact object, making it easier for the person to grasp the thing to be held. The pattern on the soles of the feet can increase friction, so that people can walk without slipping with socks and shoes, which is more effortless.

3) When people walk, there is friction between the feet and the ground, the feet push backwards hard, there is a tendency to move backwards relative to the ground, and the ground produces frictional resistance that hinders the backward movement of the feet relative to the ground, and this force moves forward, and it is this force that makes people move forward.

3 Simple mechanical.

The forearm of a person is a laborious lever. The elbow joint is its fulcrum, and when lifting something, the gravitational force of the object is the resistance acting on it, and the force exerted by the biceps brachii is its driving force.

4 Knowledge of energy.

1) When people eat food, after digestion, they turn large molecules that cannot be directly absorbed by people into small molecules that can be absorbed and used by people and enter the cells through the digestive tract, and chemical changes occur in the cells, converting biomass energy into chemical energy and being used by people.

2) The physiological curvature of human beings (cervical curvature, chest curvature, lumbar curvature and sacral curvature), as well as the curvature of human arches, femurs and tibia, just like the springs under the saddle of bicycles, can convert the kinetic energy of people's up and down movements during walking or jumping into elastic potential energy, which can effectively reduce the impact of vibration on the brain during walking.

When the whole body is musculoskeletal and muscular.

The key is to name the range of mechanics you have studied.

The phenomenon is as follows:

1. A slap does not make a sound: force is the action between objects, and the action of force is mutual. There is only one object that cannot generate force, and of course a slap will not make a sound.

2. Wind blowing grass and seeing cattle and sheep: force can change the motion state of the object, and it can also deform the object. The wind exerted a force on the grass by the flow of air, and the shape of the grass changed and bent so that it lowered its head and exposed the cattle and sheep in the grass.

3. Train: When the train comes, if the body is too close to the train, the train can take away part of the air around the body when it passes, causing a pressure difference, which will make the body move closer to the direction of the train. The faster the train passes, the more air it takes away, the greater the air pressure difference caused, and the greater the power of the body in the direction of the train, the greater the danger.

Introduction:

Mechanics The science of studying the laws of mechanical motion of matter. There are many levels of matter in nature, from the cosmic system of the universe, macroscopic celestial bodies and conventional objects, mesporal particles, fibers, and crystals, to microscopic molecules, atoms, and elementary particles. Mechanics, as it is commonly understood, is dominated by the study of natural or artificial macroscopic objects.

Almost all phenomena related to motion are inseparable from force, which is the amount that changes the state of motion of an object and the driving of a vehicle (friction, resistance, Niu II's law).

The construction of the house (the balance of forces, the balance of moments, bending and deformation), the movement of the human body, etc.

The mechanical phenomena around us have trembling:

1. Each bearing on the car drives the wheels to rotate to control the movement of the vehicle, and the power is used;

2. The construction of the house uses the balance force;

3. The blade of the kitchen knife has oil, in order to make the contact surface smooth and reduce friction when cutting vegetables;

4. The thin blade of the kitchen knife is to reduce the stress area and increase the pressure; Round Sparrow.

5. Swinging, using gravity:

6. The washing machine is dehydrated, and centrifugal force is used;

7. The banana ball when playing football uses friction and fluid force;

8. The plane flies and uses buoyancy;

9. The pattern on the wheel uses friction.

<>1. Each bearing on the car drives the wheels to rotate to control the movement of the vehicle, and the power is used;

2. The construction of the house uses the balance force;

3. The blade of the kitchen knife has oil, in order to make the contact surface smooth and reduce friction when cutting vegetables;

4. The thin blade of the kitchen knife is to reduce the stress area and increase the pressure;

5. Swinging, using gravity:

6. The washing machine is dehydrated, and centrifugal force is used;

7. The banana ball when playing football uses friction and fluid force;

8. The plane flies and uses buoyancy;

9. The pattern on the wheel uses friction.

<>1. Each bearing on the car drives the wheels to rotate to control the movement of the vehicle, and the power is used;

2. The construction of the house uses the balance force;

3. The blade of the kitchen knife has oil, in order to make the contact surface smooth and reduce the friction when cutting vegetables;

4. The thin blade of the kitchen knife is to reduce the force area and increase the pressure;

5. Swinging, using gravity:

6. The washing machine is dehydrated, and centrifugal force is used;

7. The banana ball when playing football uses friction and fluid force;

8. The plane flies and uses buoyancy; Good to know.

9. The pattern on the wheel uses friction.

1. Each bearing on the car transmits the wax and early motion belt to drive the wheel to rotate to control the movement of the vehicle, and the power is used;

2. The construction of the house uses the balance force;

3. The blade of the kitchen knife has oil, in order to make the contact surface smooth and reduce friction when cutting vegetables;

4. The thin blade of the vegetable wheel sparrow knife is to reduce the force area and increase the pressure;

5. Swinging, using gravity:

6. The washing machine is dehydrated, and centrifugal force is used;

7. The banana ball when playing football uses friction and fluid force;

8. The plane flies and uses buoyancy;

9. The pattern on the wheel uses friction.

1. Thin pieces of paper falling from a high place, even if there is no wind, the route of the paper falling is tortuous and changeable. This is due to the different convex and concave parts of the paper piece, the shape is different, so in the process of falling, the air flow velocity of various places on its surface is different, according to the principle of fluid mechanics, the flow rate is large, the pressure is small, resulting in the uneven air force everywhere on the paper, and changes with the change of the movement of the paper, so the paper continues to roll, zigzag and fall.

2. Frozen meat thaws faster in water than in air at the same temperature. Something that burns hot cools down faster in water than in air at the same temperature. A cup filled with piping hot boiling water cools down faster when immersed in water than in air at the same temperature.

The reason is that the specific heat capacity of water is larger than that of air, and the heat that can be transferred to the meat by the water drop is much higher than that of the air when the water is in contact with the same contact area.

3. Sprinkle some salt on the snowy road surface quickly, these phenomena all show that salt is used as a snow melting agent.

4. When thunder, you see lightning first, and then hear thunder, these phenomena show that light spreads faster than sound!

5. In the gas station, you will often see the warning of "prohibiting the use of plastic barrels for gasoline", using plastic barrels for gasoline, in the process of transportation, because the plastic is an insulator, it can not conduct out the charge generated by friction, and the charge accumulates more, it is easy to produce discharge, which will cause gasoline combustion and dangerous accidents.

1. Friction.

When the object being pushed and pulled moves and the object slides, it gradually slows down due to friction and finally stops.

2. Gravity. The attraction of the earth causes nearby objects to fall towards the ground. An object always moves downward when it is thrown. The object of gravity is the center of the earth. The direction of gravity is always straight downwards. The amount of gravitational force experienced by an object is directly proportional to the mass of the object.

3. Buoyancy. Ships can travel on water because of their buoyant power. Buoyancy is the difference between the upward and downward pressure of an object immersed in a liquid or gas on an object.

4. Centrifugal force.

Washing machine dehydration is the use of the principle of centrifugal movement, so that the moisture in the clothes is absorbed in the rapid centrifugal movement, so as to get out of the clothes.

5. Cycloid movement.

Swinging: If you think of the system of people and swings as a pendulum, imagine that the person squats quickly at the maximum deflection angle and stands quickly at the lowest point, and the process of squatting and standing is completed in an instant. The squatting and standing of the human body leads to the lifting of the center of mass of the system, which is equivalent to an effective pendulum length change.

Therefore, it can be seen that the sum of the work done by all external and non-conservative internal forces is equal to the increment of the mechanical energy of the particle system.

Almost all phenomena related to motion are inseparable from force, which is the amount that changes the state of motion of an object and the driving of a vehicle (friction, resistance, Niu II's law).

The construction of the house (the balance of forces, the balance of moments, bending and deformation), the movement of the human body, etc.

What is Force: Force is the action of an object on an object.

The action of forces between objects is mutual. (When an object exerts a force on another object, it is also subjected to the latter's force on it.)

Effect of force: Force can change the state of motion of an object and can also change the shape of an object. (A change in the shape or volume of an object is called a deformation.) )

The three elements of force are: the magnitude, direction, and point of action of the force, which are called the three elements of force, and they can all affect the effect.

Gravity: The force exerted by an object near the ground due to the attraction of the earth is called gravity. The direction of gravity is always straight downward.

Friction: When two objects in contact with each other are about to occur or have been in relative motion, a force will be generated on the contact surface that hinders the relative motion, which is called friction.

The amount of sliding friction is related to the roughness and pressure of the contact surface. The higher the pressure and the rougher the contact surface, the greater the sliding friction.