Given, atomic mass of monoatomic gas, m=4u Velocity of container, u=30ms−1 Final velocity of container, v=0ms−1 Let ∆T be the change in temperature and ∆U be the internal energy change. Therefore, ∆KE=∆U ‌‌=(1∕2)m(v2−u2)=nCv∆T ∆T=‌