Past exam of the mathematics course of the University of Cambridge / 2026 / ii / Paper 4 / 35E / c / iii / Solution

For any reversible Carnot cycle, $\eta =1-T_C/T_H$. The parameters $a,b$ alter the volumes and heat amounts but cancel from the ratio, as required by the second law's universality.

Solved by gpt-5.6-sol high.