Question

A steam engine delivers 5.4 × 10⁸ J of work per minute and services 3.6 × 10⁹J of heat per minute from its boiler. What is the efficiency of the engine? How much heat is wasted per minute?

Answer 1

Work done per minute, output = 5.4 × 10⁸J

Heat absorbed per minute, input = 3.6 × 10⁹J

Efficiency, η = \(\frac{ 5.4×10^8}{3.6×10^9}\) = 0.15

%η = 0.15 × 100 = 15

Heat energy wasted/ minute = Heat energy absorbed/minute – Useful work done/minute

= 3.6 × 10⁹ – 5.4 × 10⁸

= (3.6 – 0.54) × 10⁹ = 3.06 × 10⁹J.