Question 12.7:
Heat supplied from the boiler, H = 3.6 × 109 J
Efficiency of the engine = Output energy / Input energy
∴ η = W / H = 5.4 X 108 / (3.6 X 109) = 0.15
Hence, the percentage efficiency of the engine is 15 %.
Amount of heat wasted = 3.6 × 109 – 5.4 × 108
= 30.6 × 108 = 3.06 × 109 J
Therefore, the amount of heat wasted per minute is 3.06 × 109 J.
A steam
engine delivers 5.4×108 J of work per minute and
services 3.6 × 109 J of heat per minute from its
boiler. What is the efficiency of the engine? How much heat is wasted
per minute?
Solution:
Work
done by the steam engine per minute, W
= 5.4 × 108
JHeat supplied from the boiler, H = 3.6 × 109 J
Efficiency of the engine = Output energy / Input energy
∴ η = W / H = 5.4 X 108 / (3.6 X 109) = 0.15
Hence, the percentage efficiency of the engine is 15 %.
Amount of heat wasted = 3.6 × 109 – 5.4 × 108
= 30.6 × 108 = 3.06 × 109 J
Therefore, the amount of heat wasted per minute is 3.06 × 109 J.
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