Air contained within a piston-cylinder assembly undergoes three processes in series: a) process 1-2: compression at constant pressure from p1=10lbf/in2, v1=4ft3 to state 2. b) process 2-3: consant volume heating to state 3, where p3=50lbf/in2. c) process 3-1: expansion to the initial state, during which the pressure-volume relationship is pv=constant. sketch the process in series on p-v coordinates. evaluate the (a) volume at state 2, in ft3, (b) work for each process, in btu