4. (10 pts) A piston-cylinder assembly contains 2 lb of water, initially at 100 lbf/in and 400 F. The water undergoes two processes in series: a constant-pressure process followed by a constant- volume process. At the end of the constant-volume process, the temperature is 300 F and the water is a two-phase liquid-vapor mixture with a quality of 60%. Neglect kinetic and potential energy effects. a. Sketch T-v and p-v diagrams showing the key states and the processes. b. Determine the work and heat transfer for each process, all in Btu.