Q. A gas is compressed at a constant pressure of $50N/m^{2}$ from a volume of $10m^{3}$ to a volume of $4m^{3}$. Energy of $100\ J$ then added to the gas by heating. Its internal energy is
A) Increased by $400\ J$
B) Increased by $200\ J$
C) Increased by $100\ J$
D) Decreased by $200\ J$
Explanation
(a) From FLOT $\mathrm{\Delta}Q = \mathrm{\Delta}U + \mathrm{\Delta}W = \mathrm{\Delta}U + P\mathrm{\Delta}V$
$\Rightarrow 100 = \mathrm{\Delta}U + 50 \times (4 - 10) \Rightarrow \mathrm{\Delta}U = 400\ J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.