A piston/cylinder assembly is attached to a linear spring, as shown below. In addition, the atmospheric pressure p0 acts on the upper surface of the piston. The cylinder initially contains 0.1 m3 of water at 3 MPa and 400C. The system then cools down until the internal pressure reaches 1 MPa. If the piston is at the bottom of the cylinder, the force exerted by the spring is such that a pressure of 200 kPa is required to balance the forces. What is the heat transfer during the process?

Can you explain the relation between pressure and volume in this problem ?

Answer should be : -2069 kJ