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

Solution:

Given

Amount of work done by the steam engine in one minute, W = 5.4 x 108 J

Heat supplied from the boiler, H = 3.6 x 109 J

The efficiency of the engine is equal to the product of output energy and input energy.

Hence, η = W / H = 5.4 x 108 / (3.6 x 109)

On simplification, we get, = 0.15

Therefore, the percentage efficiency of the engine is 15%

Amount of heat wasted = 3.6 x 109 – 5.4 x 108 = 30.6 x 108 = 3.06 x 109 J

Hence, the amount of heat wasted per minute is 3.06 x 109 J