2.16 (a) In a reversible adiabatic expansion of an ideal gas with y = Cp/Cy independent of temperature, the pressure and volume are related by P V^{\gamma}=\text { constant }

Show that the work of adiabatic expansion from P1, V1 to P2, V2 is W = (P2 V2 – P1 V1)/(y – 1) (b) Check this equation to be sure it gives the same amount of work as Example 2.7.