Air expands adiabatically in a piston-cylinder assembly from an initial state where p1 and t1 1000 °r, to a final state where p2 60 lbf/in.2 the process is polytropic with n 1.4. the change in specific internal energy, in btu/lb, can be expressed in terms of temperature change as au (0.171) (72 - t1). determine the final temperature, in r kinetic and potential energy effects can be neglected.