Why the external work of the object decreases, and the internal energy of the object decreases ????

The external work done by the object may be done by overcoming gravity and converted into gravitational potential energy, it may be done by overcoming elastic force and converted into elastic potential energy (within elastic deformation), or it may be done by overcoming frictional force and converted into kinetic energy and heat energy generated by friction. In short, a part of the energy is converted into other forms.

Then according to the law of conservation of energy, energy is conserved. A part of the energy is transformed, and this part of the energy comes from? It can only be the internal energy of the object, i.e., the internal energy is converted into gravitational potential energy, elastic potential energy, kinetic energy, and thermal energy. Therefore, the internal energy of the object naturally decreases.

To give one of the most common examples, when drinking Sprite cans in summer, sometimes the gas is relatively full, and there is white gas on the mouth when you first open it, you can pay attention to it carefully, it is not water vapor, water vapor is invisible to our naked eye, it is due to the external work of the gas in the tank, and the internal energy suddenly decreases, so that part of the water vapor condenses into small water droplets, so we can see it with the naked eye. I think this is the most common and the best example.

1. Conservation of energy. The energy of an object is certain, and if it consumes energy by doing work externally, its own energy must be reduced. In the absence of external energy, its own energy is reduced.

2. If the other energy of the object cannot be changed, then its internal energy should be reduced, only it can be less, sorry for it.

2. If there are other energy changes, your problem conditions are not right: for example, a small ball falls from a high place to the ground and smashes the ground into a pit, it does work on the ground, but it heats up due to the impact with the ground, and the internal energy increases.

3. Another example: I fought with you, beat you badly, and did a good job to you, but I was so tired that I was out of breath, my body temperature increased, and my internal energy increased.

Because the object does work externally, the internal energy of the object is converted into mechanical energy, and because the internal energy of the object is transformed, the internal energy of the object decreases!

When an object does work externally, the internal energy must decrease, and (law of conservation of energy) does work on the object, and the internal energy increases.

The law of conservation of energy).

Energy can neither be created in a vacuum, nor disappear for no reason, but can only be transferred from one object to another, or from one form to another. Pay attention to the concept of work and energy, energy refers to the ability of an object to do work, different from work, work is only a measure and manifestation of energy transformation, energy does not mean that work must be done, and work requires conditions.

First of all, any object has internal energy, and it is constant and not zero, changing its internal energy can be done through work and heat transfer, when it does work on the outside world, it emits heat to the outside world, so the internal energy of the object decreases!

This is the law of conservation of mass and energy!

The internal energy of the object is converted into kinetic energy and heat energy emitted by the external work.

It's like you're hungry after doing exercise.

Because it converts internal energy into mechanical energy. For example, if I push you, I consume the energy in my body and push you to increase your mechanical energy

Because it converts internal energy into mechanical energy.

For example, if you have a sum of money and you give relief to a friend, you have less money.

The external work of the object may be to overcome gravity and slow down the work, which is converted into gravitational potential energy.

It may be that the work done to overcome the elastic force is converted into elastic potential energy (within the elastic deformation), or it may be to overcome the frictional force.

The work is converted into kinetic energy and heat energy generated by friction. In short, a part of the energy is converted into other forms.

Then according to the law of conservation of energy.

Energy is conserved. A part of the energy is transformed, and this part of the energy comes from? It can only be the internal energy of the object, that is, the internal energy is modulated into gravitational potential energy, elastic potential energy, kinetic energy and thermal energy. Therefore, the internal energy of the object naturally decreases.

To take the most common example, drink Sprite in the summer.

When the can, sometimes the gas is more sufficient, when you first come to open the mouth there is white gas, do not believe you can pay attention to carefully observe, that is not the spring gas of water steam, water vapor we can not see with the naked eye, that is because the gas in the tank does external work, the internal energy suddenly decreases, so that part of the water vapor condenses into small water droplets, so we can see it with the naked eye. I think this is the most common and the best example.

The internal energy of an object that does work on an object does not necessarily increase.

If only the work of initiation is done on the object and the work is not done externally, or if the object does not transfer the internal energy outward through heat transfer, then there will be no increase. For example, when doing work on an object, if a person lifts the object high, then the result of doing work on the object is that the biological energy of the person is consumed and converted into the mechanical energy of the object, but it is not converted into the internal energy of the object, so the internal energy of the object does not increase.

Doing work is energy transformation:

Different forms of energy in nature correspond to different forms of motion: the motion of objects has mechanical energy, the motion of molecules has internal energy, the motion of electric charges has electrical energy, the motion of the nucleus of the nucleus has atomic energy, and so on.

Different forms of energy difference can be converted into each other: "Frictional heat generation is the conversion of mechanical energy into internal energy by overcoming friction and doing work; When the water in the kettle boils, the water vapor does work on the lid of the kettle to lift the lid up, indicating that the internal energy is converted into mechanical energy; The electric current does work through the heating wire, which converts electrical energy into heat energy, and so on."

These examples illustrate the process by which different forms of energy can be converted into each other and by doing work, which is the amount of energy converted.

Not necessarily. The energy of an object is not only internal energy, but also balances with energy, and other energy may also be reduced.

For example, if an object has an initial velocity and advances against another object in a rough plane, the kinetic energy decreases and the internal energy increases (frictional thermogenesis). Another situation: compress the water bottle, push the cap out to see the water mist, is the internal energy is reduced.

There is a premise for this conclusion to be true, that is, the system is independent. That is, the outside world has no influence on it, and the external work is done at this time, and the internal energy of the system is reduced. However, without this premise, it will not be established, for example, the external heating of the system, and the system will do external work, and the internal energy may not be reduced.

Not necessarily. This sentence does not mean that the internal energy of the work done to the object must increase, or the internal energy of the external work of the object must decrease. For example, if an object is lifted to starve, the object only increases the gravitational potential energy, but does not increase the internal energy.

An object that is lifted accidentally falls and hits you, and the work done by the object on you only reduces the mechanical energy, but does not reduce the internal energy.

The internal energy of an object should include the sum of energies such as kinetic energy, potential energy, chemical energy, ionization energy, and nuclear energy inside the nucleus of all the microscopic particles in it.

However, in the process of changing the general thermodynamic state, the molecular structure, atomic structure and nuclear structure of matter do not change, so these energy changes can not be considered. However, when it comes to shading and chemical reactions in thermodynamic research, it is necessary to include chemical energy in internal energy.

Not necessarily. Doing slip Kaigong is one of the two ways to change the internal energy of an object. This sentence does not mean that the internal energy of the body must be increased, or the internal energy of the external work of the object must be reduced.

For example, when an object is lifted, the object only increases the gravitational potential energy, but does not increase the internal energy. An object that was lifted accidentally fell and hit you, and the work done by the object on you only reduced the mechanical energy, but did not reduce the internal energy.

When work is done on an object, the internal energy of the object increases; When an object does work externally, the internal energy of the object decreases. This passage refers to the fact that in overcoming the work done by friction and the work done by compressed gas, the internal energy of the object must increase; In the phenomenon of gas expansion doing external work, the internal energy of the gas will definitely decrease.