Question

An engine does 3250 J of work and discards 5750 J of heat. Find the efficiency of this engine.

Answer 1

Let's first find the quantity of heat that supplied to the engine in each cycle:

$$W=Q_H-Q_C,$$ $$Q_H=W+Q_C=3250\ J+5750\ J=9000\ J.$$

Finally, we can find the efficiency of the engine:

$$e=\dfrac{W}{Q_H}\times100\%=\dfrac{3250\ J}{9000\ J}\times100\%=36\%.$$