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.

Process		ΔU	Q	WON
isobaric	expansion	+[1]	+	−
	compression	−[2]	−	+
isochoric	cooling	−	−	0
	heating	+	+	0
isothermal	expansion	0	+	−
	compression	0	−	+
adiabatic	expansion	−	0	−
	compression	+	0	+

Let’s look at each of them in detail in the following sections.

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[1]The internal energy must increase since p is constant and V has increased, and .

[2] same logic as that for isobaric expansion.

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