question_answer

The temperature-entropy diagram of a reversible engine cycle is given in the figure. Its efficiency is

A)  1/2                                       

B)  1/4                       

C)        1/3                       

D)        2/3

Correct Answer: C

Solution :

According to the figure \[{{v}_{app}}=|{{v}_{1}}|+|{{v}_{2}}|=\sqrt{\frac{2G}{r}({{m}_{1}}+{{m}_{2}})}\] \[l={{10}^{-4}}m,\,\,F=20N,\] \[A={{10}^{-6}}{{m}^{2}},L=1m\] \[\therefore \] \[Y=\frac{FL}{Al}\] \[=\frac{20\times 1}{{{10}^{-6}}\times {{10}^{-4}}}\]