Question

A Carnot engine takes 900 kcal of heat from a reservoir at 723C and exhausts it to a sink at 30C. The work done by the engine is:

• A. $2.73\times {10}^6$ Cal
• B. $3.73\times {10}^6$ Cal
• C. $6.27\times {10}^6$ Cal
• D. $5.73\times {10}^6$ Cal

Answer 1

Answer: (C)

$6.27\times {10}^6$ Cal

$Q_H=Q_{reservoir}=300Kcalat723°C{T}_{sink}=T_L=30°C\frac{Q_L}{Q_H}=\frac{T_L}{T_H}\Rightarrow \frac{Q_1}{900}=\frac{(30+273)}{(723+273)}\Rightarrow Q_2=\frac{303\times 900}{996}=273.795W=Q_H-Q_l=(900-273.8)Kcal=626.2Kcal=6.26\times {10}^{5}cal$