일반물리학 1 — Entropy and the Second Law of Thermodynamics: Problem 40

40 A two-stage Carnot engine consists of two Carnot cycles: In stage 1, a Carnot cycle absorbs heat at temperature \(T_1 = 500 \text{ K}\) and discharges heat at temperature \(T_2 = 400 \text{ K}\). In stage 2, a Carnot cycle absorbs that discharged heat at \(T_2\) and then discharges heat at temperature \(T_3 = 300 \text{ K}\). What is the efficiency of the engine?