Apolytropic process is one in which p vn = p1v n 1 = p2v n 2 = constant at all points in the process, where v = v /m is the specific volume of the substance. the exponent n is constant and depends on the nature of the process; for an ideal gas, isothermal process, for example, n = 1. say a substance is compressed from p1 = 100 kpa, v1 = 0.5 m3/kg to p2 = 300 kpa in a polytropic process for which n = 1.4. calculate the work performed during the compression, per unit mass. the integral formula for work per unit mass is obtained by dividing eq. (1) by the system mass, for which dv /m → dv and w1−2/m → w1−2.