Halliday, Resnick & Walker — Entropy and the Second Law of Thermodynamics: Problem 32

A Carnot engine is set up to produce a certain work \( W \) per cycle. In each cycle, energy in the form of heat \( Q_H \) is transferred to the working substance of the engine from the higher-temperature thermal reservoir, which is at an adjustable temperature \( T_H \). The lower-temperature thermal reservoir is maintained at temperature \( T_L = 250 \text{ K} \). Figure 20.10 gives \( Q_H \) for a range of \( T_H \). The scale of the vertical axis is set by \( Q_{Hs} = 6.0 \text{ kJ} \). If \( T_H \) is set at \( 550 \text{ K} \), what is \( Q_H \)?