Q. A gas undergoes a change of state during which $100\ J$ of heat is supplied to it and it does $20\ J$ of work. The system is brought back to its original state through a process during which $20\ J$ of heat is released by the gas. The work done by the gas in the second process is
A) $60\ J$
B) $40\ J$
C) $80\ J$
D) $20\ J$
Explanation
(a) In a cyclic process $\mathrm{\Delta}U = 0 \Rightarrow \mathrm{\Delta}Q = \mathrm{\Delta}W$
$\Rightarrow (100 - 20) = 20 + W_{2} \Rightarrow W_{2} = 60\ J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.