Question

What condition is necessary for two bodies that are in physical contact with each other to be in thermal equilibrium?

Answer 1

They must be able to exchange heat energy, i.e. they must not be separated by an adiabatic (insulating) wall.

Answer 2

They must have the same temperature.

Answer 3

Ah, that's a better answer, Vincent. I read the question as "..to come to thermal equilibrium." But read properly, they can only be in thermal equilibrium if they are at the same temperature.

Answer 4

That's also how I read the question the first time I saw it!
In short:
- thermal equilibrium require same temperature
- mechanical equilibrium requires same pressure

Answer 5

Ok thank You!