Exercises for chapter 31. Two kilograms of water at 120◦C with a quality

of 25% has its temperature raised 20◦C in a constant volume process. What are the heat transfer and work in the process? (ans: 878 kJ)

2. A piston/cylinder contains 1.5 kg of water at 200 kPa, 150◦C. It is now heated by a process in which pressure is linearly related to volume to a state of 600 kPa, 350◦C. Find the final volume, the heat transfer, and the work in the process. (ans: W= −291.24 kJ and Q = 165.1 kJ )

Exercises for chapter 2

3. A piston/cylinder device contains 50 kg water at 200 kPa with a volume of 0.1m3. Stops in the cylinder are placed to restrict the enclosed volume to a maximum of 0.5 m3. The water is now heated until the piston reaches the stops. Find the necessary heat transfer. (Q= 995 kJ )

4. A 25 kg mass moves at 25 m/s. Now a brake system brings the mass to a complete stop with a constant deceleration over a period of 5 s. Assume the mass is at constant P and T. The brake energy is absorbed by 0.5 kg of water initially at 20◦C and 100 kPa. Find the energy the brake removes from the massand the temperature increase of thewater, assuming its pressure is constant. (ans: 7.8125 kJ , 3.7oC )