Question

For an ideal heat engine, the temperature of the source is $127$$º\mathrm{C}$. In order to have $60$$\%$ efficiency, the temperature of the sink should be ________ºC. (Round off to the Nearest Integer)

Answer 1

The temperature of sink would be:

$$\begin{gathered} Step1:\eta =(1=T_2/T_1) \\ Step2:0.6=1-T_2/400 \\ 0.6-1=-T_2/400 \\ -0.4\times 400=-T_2 \\ {T}_2=160K \\ {T}_2=160-273=-{113}^{\circ }C \end{gathered}$$

For an ideal heat engine, the temperature of the source is $127$ºC. In order to have $60$% efficiency the temperature of the sink should be $-113°C$.