Question

An engine absorbs 2000J of heat from a hot reservoir and expels 750J to a cold reservoir during each operating cycle. How much work is done during the cycle? And what is the power output of the engine if each cycle last for 0.5 seconds?

Answer 1

Question 31993

The amount of work, done during the cycle is $A = Q_{1} - Q_{2}$, where $Q_{1}$ is the amount of heat, that engine absorbs from hot reservoir (2000J), and $Q_{2}$ is the amount of heat that the engine expels (750J). Thus, $A = 2000J - 750J = 1250J$ - this is the work done during cycle.

The power $N$ by definition is $N = \frac{A}{t}$. Knowing the work done during the cycle and the time of cycle, obtain $N = \frac{1250J}{0.5s} = 2500\frac{J}{s}$ - this is the power output of the engine.