## Essential University Physics: Volume 1 (4th Edition)

(a)$598 J$ (b)$2500J$ Heat flows into gas.
(a) We know that $W_{BC}=-P(V_C-V_B)$ $\implies W_{BC}=-250KPa(1L-5L)=1KJ$ $W_{CA}=-nRT\ln \frac{V_A}{V_C}=-P_AV_A\ln \frac{V_A}{V_C}=-50\times 5\ln \frac{5}{1}=-402$ $W_{cycle}=1000J-402J=598J$ (b) As $Q_{AB}=\frac{5R}{2}(\frac{P_BV_B}{R}-\frac{P_A V_A}{R})$ $Q_{AB}=\frac{5}{2}(250KPa\times 5L-50KPa\times 5L)=2500J$ Thus, heat flows into gas.