Air expands adiabatically in a piston-cylinder assembly from an initial state where p1 = 100 lbf/in. 2, v1 = 3. 704 ft3/lbm, and t1 = 1000 or, to a final state where p2 = 50 lbf/in. 2 the process is polytropic with n = 1. 4. The change in specific internal energy, in btu/lbm, can be expressed in terms of temperature change as du = (0. 171)(t2-t1). Determine the final temperature (in or). Kinetric and potential energy effects can be neglected.