Air, an ideal gas, is isentropically compressed from V1 = 0.36 ft3, P1 = 14.5 psia, T1 = 70°F, to V2 = 0.03 ft3(compression ratio = 12). Find T2, P2, and W (work in Btu) for this process: (a) assuming constant specific heat ideal gas with cp = 0.24 Btu/lbm-R, cv = 0.171 Btu/lbm-R and k = 1.4 (room temperature values), and (b) assuming variable specific ideal gas.