Q. The volume of air increases by 5%, in its adiabatic expansion. The percentage decrease in its pressure will be
A) 5%
B) 6%
C) 7%
D) 8%
Explanation
(c) $PV^{\gamma} = K$ or $P\gamma V^{\gamma - 1}dV + dP.V^{\gamma} = 0$
$\Rightarrow \frac{dP}{P} = - \gamma\frac{dV}{V}$ or $\frac{dP}{P} \times 100 = - \gamma\left( \frac{dV}{V} \times 100 \right)$
$= - 1.4 \times 5 = 7\%$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.