Question

When two bodies A and B are in thermal equilibrium, then

• A. The internal energy of the two bodies will be equal
• B. The kinetic energy of all the molecules of A and B will be equal
• C. The potential energy of all the molecules of A and B will be equal
• D. The average kinetic energy of the molecules of the two bodies will be equal

Answer 1

The correct option is A

The internal energy of the two bodies will be equal

Thermal equilibrium:

1. When two bodies are in thermal equilibrium, it means no heat is exchanged between them, and it is possible only if they both are at the same temperature.
2. Now two bodies A and B have the same temperature.
3. We know that the internal energy of a system is directly related to its temperature.
4. As both A and B have the same temperature, so they have the same internal energy.

Hence, the internal energy of the two bodies will be equal, if they are in thermal equilibrium.