Answer to Question #134108 in Molecular Physics | Thermodynamics for viccy

Question

explain zeroth law of thermodynamics.

Answer 1

The zeroth law of thermodynamics states: if body A is in thermal equilibrium with body B, and body B is in thermal equilibrium with body C, then A and C are in thermal equilibrium.

It might seem obvious from mathematical point of view, but not from physical one. For example, if we have body A with charge +q, body B with -q and body C with +q, relations A to B and B to C are the same, but relation of A to C is not the same as all others.

The zeroth law of thermodynamics gives us notion of two things: 1) the nature of transferred heat is the same for all bodies (based on conception of heat equilibrium), 2) there exist a certain single-valued function of the thermodynamic states of the assemblies, which may be called the temperature t.