1. An engine using a polyatomic (atoms not in a row) ideal gas is driven by this cycle: from A to B, the pressure increase to 3 times its original pressure while keeping V constant; from B to C, it expands adiabatically until it reaches 4 times the original volume; from C to D, the pressure drops at constant V; from D to A it contracts adiabatically.
(a) Sketch the cycle, indicating P, V, and T, for all points.
(b) What is the efficiency of this cycle?
(c) What's the maximum efficiency possible between the high and low temperatures. (Leave all answers in terms of the original P, V, and T.)