wab = Pa(v b-Va)= 1

Change of internal energy: △ e = 5nr (TB-ta)/2 = 5 (PVB-PVA)/2 = 5wab/2.

So Q 1=Wab+△E= 7Wab/2.

B-c is an isovolumic process;

WBC = 0△E = 5nR(Tc-Tb)/2 = 5(PbVb-PcVc)/2 = Q2

C-A is an isothermal process: PV=PcVc, so P = PCVC/V.

WCA =∫PdV = PcVc∫( 1/V)dV = PcVc ln(Va/Vc)=-pcvcln 2

△E=0, so Q3=Wca=-PcVcln2.

Cycle efficiency: η = (WAB+WBC+WCA)/(Q1+Q2+Q3)