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Question: Answered & Verified by Expert
A Carnot's engine operates with source at $127^{\circ} \mathrm{C}$ and sink at $27^{\circ} \mathrm{C}$. If the source supplies $40 \mathrm{~kJ}$ of heat energy, the work done by the engine is
PhysicsThermodynamicsKCETKCET 2007
Options:
  • A $30 \mathrm{~kJ}$
  • B $10 \mathrm{~kJ}$
  • C $4 \mathrm{~kJ}$
  • D $1 \mathrm{~kJ}$
Solution:
2169 Upvotes Verified Answer
The correct answer is: $10 \mathrm{~kJ}$
Efficiency $\eta=1-\frac{T_{2}}{T_{1}}$
$$
=1-\frac{(273+27)}{(273+127)}=1-\frac{300}{400}=\frac{1}{4}
$$
$$
\begin{aligned}
\eta &=\frac{\text { Work done }}{\text { Heat supplied }} \\
\frac{1}{4} &=\frac{W}{40} \Rightarrow W=10 \mathrm{~kJ}
\end{aligned}
$$

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