Question

 A Carnot engine receives 4000 J of heat from a reservoir at 500 K, does some work, rejects 2000 J heat to reservoir at 200 K.

1. How much work does it do?
2. What is its efficiency?

Answer 1

Given: Q_H = 4000 J

Q_C = −2000 J

T_C = 200 K

T_H = 500 K

To find: W = ? and η = ?

Formula: W = Q_H + Q_C

= 4000 + (−2000)

= 2000 J 

The efficiency of the Carnot engine is:

η = `1 - T_C/T_H`

= `(T_H - T_C)/T_H`

= `(500 - 200)/500`

= `300/500`

= 0.6 

= 60 %