Question

A heat engine with an efficiency of $40\%$ does $100J$ of work per cycle. The amount of heat exhausted in $\left(J\right)$ to the cold reservoir per cycle is

Answer 1

Given,

Efficiency of the cycle, $\eta =40\%$

Work Output, $W=100J$
Then,

$\eta =\frac{W}{Q_{input}}=\frac{40}{100}=\frac{100}{Q_{input}}$

$\Rightarrow Q_{input}=250J$

Heat rejected, $Q_{rejected}=Q_{input}-W$

$Q_{rejected}=250-100=150J$

Final answer: $150$