# 11.5.1 Thermodynamic Processes

There are four kinds of thermodynamics processes that occur frequently in practical situations, namely:

Isobaric:          constant pressure       ($\displaystyle {{W}_{{ON}}}=-p\Delta V$ )

Isochoric:        constant volume          ($\displaystyle {{W}_{{ON}}}=0$ )

Isothermal:      constant temperature  ($\displaystyle \Delta U=0$ )

Adiabatic:        zero heat transfer       ($\displaystyle Q=0$ )

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.

[1]The internal energy must increase since p is constant and V has increased, and $\displaystyle pV=nRT$ .

[2] same logic as that for isobaric expansion.