There are four kinds of thermodynamics processes that occur frequently in practical situations, namely:
Isobaric: constant pressure ( )
Isochoric: constant volume ( )
Isothermal: constant temperature ( )
Adiabatic: zero heat transfer ( )
The tables below summarize the signs of the terms in the first law for the different processes.
Let’s look at each of them in detail in the following sections.
The internal energy must increase since p is constant and V has increased, and .
 same logic as that for isobaric expansion.