If a system expands in volume by an amount AV(m]) against a constant restraining pressure P(N/m?), a quantity PAV(J) of energy is transferred as expansion work from the system to its surroundings. Suppose that the following four conditions are satisfied for a closed system: (a) the system expands against a constant pressure (so that AP = 0); (b) AEx = 0; (c) AE, = 0; and (d) the only work done by or on the system is expansion work. Prove