A heat engine absorbs 1,200 J of heat from a hot reservoir per cycle and does 360 J of work per cycle. What is the efficiency of this heat engine?
Explanation
📌 Efficiency e = W/Q_h = 360/1200 = 0.30 = 30%. Distractor B added W to denominator (wrong ratio: W/(Q_h + W)); D reported (Q_h − W)/Q_h = 70% — that’s the waste-heat ratio, not efficiency.