Q. A gas under constant pressure of $4.5 \times 10^{5}$ Pa when subjected to 800 kJ of heat changes the volume from $0.5m^{3}$ to $2.0m^{3}$. The change in the internal energy of the gas is
A) $6.75 \times 10^{5}\ J$
B) $5.25 \times 10^{5}\ J$
C) $3.25 \times 10^{5}\ J$
D) $1.25 \times 10^{5}\ J$
Explanation
(d) Here, $p = 4.5 \times 10^{5}\ Pa$,
$dV = (2.0 - 0.5)m^{3} = 1.5\ m^{3}$
$dU = ?,\ dQ = 800\ kJ = 8 \times 10^{5}\ J$
$dW = pdV = 4.5 \times 10^{5} \times 1.5 = 6.75 \times 10^{5}\ J$
$dU = dQ - dW = 8 \times 10^{5} - 6.75 \times 10^{5}$
$= 1.25 \times 10^{5}\ J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.