Q 11-12-161JEE MainJEE Main 2025 (2 Apr, Shift 2)Easy
The internal energy of air in a $4\ \text{m}\times4\ \text{m}\times3\ \text{m}$ sized room at 1 atmospheric pressure will be ______ $\times10^6\ \text{J}$. (Consider air as a diatomic gas; take $1\ \text{atm} = 10^5\ \text{Pa}$)
Numerical value type. Enter your answer.
Answer: 12
For a diatomic gas (5 degrees of freedom), $U = \tfrac52 nRT = \tfrac52 PV$.
$V = 4\times4\times3 = 48\ \text{m}^3$:
$$U = \tfrac52\times10^5\times48 = 1.2\times10^7\ \text{J} = 12\times10^6\ \text{J}$$
Solution by Sreeraj P, M.Sc Physics