Basic Thermodynamic Processes

A thermodynamic process moves a system from one thermodynamic state to another.

Why should we care about thermodynamic processes?

Answer: What happens inside any engine?   Thermodynamic processes!   compression, expansion, heating, combustion, etc.

Generally we consider quasi-static processes, where the state changes so slowly that we can regard the gas as always being in equilibrium.

The PV diagram

It is useful to follow ideal-gas processes in the PV diagram. Using the ideal gas law PV=nRT, the temperature is known for any P and V, from which the state of a gas is uniquely determined.