Past exam of the physics course of the year 4 of the natural sciences course of the University of Cambridge / 2015 / Paper 1 / Section B / B3 / d / Solution

The depicted endpoints have $P_2>P_1$ and $T_2>T_1$. For positive thermal expansion coefficient,Thus path (b) requires the least work on the solid, path (a) the most, and path (c) lies midway between them. Heating at the higher pressure produces more negative work on the system. The ordering would reverse for a negative expansion coefficient; if the product vanishes, the paths have equal work in this approximation.