Physics - Heat & Thermo Question with Solution | TestHub

Internal energy is the energy due to thermal motion.

The internal energy of an ideal gas given by

$U=\frac{f}{2}nRT$ (for $n \mathrm{moles}$)

$U=\frac{f}{2}\left(PV\right)=\frac{f}{2}\times P\times \frac{M}{\mathrm{\rho }}$ (Since, $f=3$ for a monoatomic gas.)

$U=\frac{3}{2}\times 4\times {10}^4\times \frac{2}{8}$

$=1.5\times {10}^{4}J$
So, the order of energy due to thermal motion is ${10}^4$