Vibrational kinetic energy is insignificant at low temperatures.
Interatomic forces are responsible for vibrational kinetic energy.

Vibrational energy is

In free vibrations, energy

The average rotational kinetic energy of hydrogen molecule at a temperature T is E . The average translational kinetic energy of helium at same temperature will be:

The average rotational kinetic energy of hydrogen molecule at a temperature T is E . The average translational kinetic energy of helium at same temperature will be:

Mechanical energy and kinetic energy

(A): According to the law of equipartition of energy, internal energy of an ideal gas at a given temperature, is equally distributed in translational and rotational kinetic energies. (R) : Rotational kinetic energy of a mono. atomic gas is equal to its translational kinetic energy