Give a qualitative explanation of how frictional forces between moving surface produce internal energy. Why does the reverse process (internal energy producing relative motion of those surface) not occur?

							Energy possessed by the atoms or molecules by virtue of their motion is called kinetic energy. Since the two moving surfaces are acted by a frictional force between them, therefore there is a force of attraction between the molecules of two surfaces. Thus, they possess some potential energy. Sum of the total kinetic and potential energies of atoms or molecules constituting the system are called the internal energy of the system. Again due to the frictional force between the two surfaces, there will be the increase of thermal energy of the system. Since thermal energy is the part of internal energy which is transferred from one surface to another on account of the temperature difference, therefore frictional force between moving surfaces produce internal energy.
Frictional force between two surfaces produces thermal energy. But the thermal energy is the part of internal energy. Therefore the reverse process (internal energy producing relative motion of those surfaces) will not occur