Question

The difference of temperature between a hot and a cold body is 120°C .If the heat engine is 30% efficient the temperature of cold body will be?

Answer 1

Answer:

7°C

Explanation:

Let the temperature of the cold body = t°C

Then the temperature of the hot body = (t + 120)°C

Efficiency of heat engine η = 1 - T₂/T₁

T₁ = (t + 120 + 273) K

T₂ = (t + 273) K

Therefore , 30% = 1 - (t + 273)/(t + 393)

=> 30/100 = 1 - (t + 273)/(t + 393)

=> t = 7°C