Ammonia in a piston–cylinder assembly undergoes two processes in series. initially, the ammonia is saturated vapor at p1 5 100 lbf/in.2 process 1–2 involves cooling at constant pressure until x2 5 75%. the second process, from state 2 to state 3, involves heating at constant volume until x3 5 100%. kinetic and potential energy effects are negligible. for 1.2 lb of ammonia, determine (a) the heat transfer and work for process 1–2 and (b) the heat transfer for process 2–3, all in btu.

A60-kg box is being pushed a distance of 6.8 m across the floor by a force p with arrow whose magnitude is 162 n. the force p with arrow is parallel to the displacement of the box. the coefficient of kinetic friction is 0.24. determine the work done on the box by each of the four forces that act on the box. be sure to include the proper plus or minus sign for the work done by each force. (the floor is level and horizontal. forces that act on the box: pushing force p, frictional force f, normal force n, and weight mg.)