Does an object with a high temperature have to be larger than an object with a low temperature?

The internal energy of an object is the sum of the total kinetic energy and the potential energy of the molecular thermal motion. Macroscopically, the internal energy is related to the number of molecules, temperature, and volume of the object.

Therefore, the internal energy of an object with a high temperature is not necessarily greater than that of an object with a lower temperature.

Internal energy is the sum of all forms of motion of all microscopic particles in an object or a system composed of several objects (referred to as a system). Internal energy is often represented by the symbol u, internal energy has a dimension of energy, and the SI unit is joules (j) [Note: Because the molecule is constantly doing irregular motion, the internal energy can be '0' (this motion is called molecular thermal motion)].

According to the first law of thermodynamics, internal energy is a function of state. At the same time, internal energy is a broad physical quantity, that is, the total internal energy of the two parts is equal to the sum of their respective internal energies.

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Not necessarily, for example, a very hot small iron nail is compared to a large iceberg. Internal energy is not only related to temperature, but also to mass, state, and volume.

The internal energy of an object is the sum of the kinetic energy, potential energy and internal electronic energy of all molecules and atoms that make up the object, and the change of the internal energy of the object can be achieved through the energy exchange of the regular motion of molecules and atoms, or through the energy exchange of the irregular motion of molecules and atoms (or both). The former energy exchange method is the way of doing macroscopic mechanical work, and the latter energy exchange mode is the so-called heat transfer. More precisely, heat transfer is the process by which internal energy is transferred from one object to another, or from one part of an object to another, without macroscopic mechanical work.

It is achieved through three ways: heat conduction, convection, and heat radiation. In the actual heat transfer process, these three methods are often carried out together, and it is important to see which one is dominant. In thermodynamics, all other modes of energy transfer except heat transfer are attributed to work.

So, heat transfer and work are the two ways in which energy is transferred, and there is no other way.

Not necessarily, the number of molecules should be compared.

n- The amount of matter.

r - ideal gas constant.

t-thermodynamic temperature.

Generally i r are constants, t and n are variables, and the two variables determine the internal energy of the object. Therefore, a high-temperature object does not necessarily have a larger internal energy than a low-temperature object.

Definition of internal energy: Internal energy is the sum of the energy of all forms of motion of all microscopic particles in an object or a system composed of several objects (referred to as a system).

From the definition, it can be seen that the magnitude of internal energy is not only related to the temperature of the object, but also has a great relationship with the number of microscopic particles.

Therefore, the internal energy of a tiny high-temperature object (with few microscopic particles) can be greater than that of a high-temperature object compared to a very large low-temperature object (with many microscopic particles).

Not necessarily, the magnitude of internal energy is not only related to temperature, but also related to the number of molecules and the state of matter, for example, the internal energy of a drop of boiling water is much smaller than the internal energy of an iceberg.

The pathway of internal energy change.

1. Doing work can change the internal energy of an object. When the external force does positive work on the object, the internal energy of the object increases, and vice versa. Prepare for burial.

2. Heat transfer can change the internal energy of an object. There are three forms of heat transfer: heat conduction, heat convection (generally found in gases and liquids), and thermal radiation. The condition for heat transfer is that there must be a temperature difference between the objects.

The kinetic energy of the molecule and the potential energy of the molecule inside the object are collectively referred to as matter.

The internal energy of the body. The motion of the molecule is thermal motion, and the temperature of the object is a polymer.

The motion of the molecule will accelerate the kinetic energy of the molecule to become larger, inside the object.

can increase; The movement of molecules when the temperature of the object decreases.

The kinetic energy of the molecule will slow down, and the internal energy of the object will also decrease.

will decrease. As the temperature of the object decreases, the internal energy must decrease.

If the relationship between these three is explained in detail, there are six sentences, only one sentence in the middle of the period is correct, and the remaining five sentences are all wrong: if the temperature of the object increases, the internal energy of the object must increase; Because (the mass, Chizhou's state does not change, the higher the temperature, the greater the internal energy), the temperature of the object increases, then the object must absorb heat; Because the temperature of the object rises and the outside world does work on the object. )

If the internal energy of the object increases, the temperature of the object must increase; ✘

Because the internal energy of the object increases, it is possible that the object has undergone a disturbance change in the state of matter, or the mass has changed. If the internal energy of the object increases, the object must have absorbed heat; (The increase in the internal energy of the object may also be due to the work done by the outside world on the object).

If the object absorbs heat, the temperature of the object must increase; (When melting, the temperature of the object does not change) If the object absorbs heat, the internal energy of the object must increase. (When absorbing heat, external work may be done, and internal energy may not necessarily increase.) )

This can only be said to be generally true, not absolutely. There are counterexamples when the actual gas cannot be approximated as an ideal gas, but it is not easy for middle school students to understand the counterexample accurately. For example, when the actual gas temperature increases slightly, and the volume changes greatly, the kinetic energy of irregular motion only increases slightly, and the potential energy reduction caused by the volume change can be very large, so that the internal energy does not necessarily increase.

For more rigorous proofs, calculus is required. For liquids and solids, when phase transitions are not involved, the volume change in the process is usually very small, and the molecular potential energy changes little, which is basically negligible, so the increase in temperature can almost be regarded as an increase in internal energy, but there are still exceptions in extreme cases.

If you have any questions, please feel free to ask. ,10,Is it correct that the higher the temperature of the same object, the greater the internal energy?

That's what the teacher said in class, but I think it's just an increase in the kinetic energy of the molecule, why can't the potential energy of the molecule decrease?

There are answers on the Internet that say that they are correct, and some say that according to the first law of thermodynamics, the internal energy of an object is determined by the average kinetic energy and the potential energy of the molecule.

Therefore, when the temperature of an object increases, it can only be said that its average kinetic energy increases, while the internal energy does not necessarily increase. Which one is right!

The diagram of the relationship between internal energy, heat and temperature is as follows:

If the temperature of the object increases, the internal energy of the object must increase; (Quality, state unchanged, high temperature, large internal energy).

If the temperature of the object increases, the object must absorb heat; (An increase in the temperature of an object may also be a result of work done on the object by the outside world.) )

If the internal energy of the object increases, the temperature of the object must increase; (As the internal energy of an object increases, the state of matter of the object may have changed, or the mass of the object has changed.) )

If the internal energy of the object increases, the object must have absorbed heat; (The increase in the internal energy of the object may also be due to the work done by the outside world on the object).

If the object absorbs heat, the temperature of the object must increase; (When melting, the temperature of the object remains unchanged).

If the object absorbs heat, then the internal energy of the object must increase. (When absorbing heat, external work may be done, and internal energy may not necessarily increase.) )

The temperature is high enough to combrate the oxygen in the air into flames, and the heat transfer can cause the matter to melt and melt to the extreme, destroying the matter (mass) and energy.

The temperature is low to a certain extent, it can solidify with water or air or water in the body (blood) to transfer cold, ice deficiency and freezing can lead to the fragmentation of matter, cold to the extreme of the empty calendar, and the mass and energy of matter, all life-threatening can change the speed of movement (movement) of objects.