Question

A steam engine delivers $5.4\times 10{}^8$ J of work per minute and services $3.6\times 10{}^9$ J of heat per minute from its boiler. What is the efficiency of the engine? How much heat is wasted per minute?

Answer 1

The efficiency is given by
$\eta =\frac{\text{Work done}}{\text{Energy}}$
$\eta =\frac{5.4\times {10}^8}{3.6\times {10}^9}=0.15=15\%$
Energy wasted $=3.6\times {10}^9-5.4\times {10}^8=3.06\times {10}^{9}J$