There is n moles of the monoatomic gas in the container. Molar mass of the gas = m, Total mass of the gas in the container, M = mn Change in KE of the gas when the container is suddenly stopped, i.e.,
∆K=(KE)initial−(KE)final=
1
2
Mv02−0 =
1
2
Mv02=
1
2
Mv02
This change in kinetic energy (∆K) result in a change in internal energy (∆U) of the gas ∆U=nCv∆T=n(
3
2
R)∆T Here, ∆T is the change in temperature of the gas As