Chapter 2 - Problems: Developing Engineering Skills - Page 89: 2.81

we all know that , efficiency = $W_{cycle}$/$Q_{in}$ so , $Q_{in}$ = $W_{cycle}$/efficiency , Here , efficiency = 0.4 , $W_{cycle}$= 10000 kJ $Q_{in}$ = (10000 kJ)/(0.4) = 25000kJ here , $W_{cycle}$ = $Q_{cycle}$ = $Q_{in}$ - $Q_{out}$ thus , $Q_{out}$ = $Q_{in}$ - $W_{cycle}$ = 25000 - 10000 =15000 kJ.

we all know that , efficiency = $W_{cycle}$/$Q_{in}$ so , $Q_{in}$ = $W_{cycle}$/efficiency , Here , efficiency = 0.4 , $W_{cycle}$= 10000 kJ $Q_{in}$ = (10000 kJ)/(0.4) = 25000kJ here , $W_{cycle}$ = $Q_{cycle}$ = $Q_{in}$ - $Q_{out}$ thus , $Q_{out}$ = $Q_{in}$ - $W_{cycle}$ = 25000 - 10000 =15000 kJ.