Internal pressure

Internal pressure is a measure of how the internal energy of a system changes when it expands or contracts at constant temperature. It has the same dimensions as pressure, the SI unit of which is the pascal.Dividing this equation by d ⁡ V {displaystyle operatorname {d} V} at constant temperature gives: Internal pressure is a measure of how the internal energy of a system changes when it expands or contracts at constant temperature. It has the same dimensions as pressure, the SI unit of which is the pascal. Internal pressure is usually given the symbol π T {displaystyle pi _{T}} . It is defined as a partial derivative of internal energy with respect to volume at constant temperature: π T = ( ∂ U ∂ V ) T {displaystyle pi _{T}=left({frac {partial U}{partial V}} ight)_{T}}