Chapter 21 - Heat Engines and Refrigerators - Exercises and Problems - Page 594: 7

a) $ W = 12.5 kJ$ b) $Q_2 = 50kJ$

We have $ P =\frac{W}{t}$ For $2400 rpm$ $P= 500kW$ a) For one cycle $ P = \frac{500kW}{2400}$ $P = 5/24kW $ Thus $W = P*t = 5/24 kW *1m$ $ W= 5/24kW *60s$ $ W = 12.5 kJ$ b)Also $ \eta =\frac{ W}{Q_1}$ $20\% = \frac{12.5kJ}{Q_1}$ $Q_1 = 62.5kJ$ and $W= Q_1-Q_2$ $Q_2 = 62.5kJ - 12.5kJ$ $Q_2 = 50kJ$