2 Small smooth spheres \(A\) and \(B\), of equal radii and of masses 6 kg and 2 kg respectively, lie on a smooth horizontal plane. Initially \(A\) is moving towards \(B\) with speed \(5 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) and \(B\) is moving towards \(A\) with speed \(3 \mathrm {~m} \mathrm {~s} ^ { - 1 }\). After the spheres collide, both \(A\) and \(B\) move in the same direction and the difference in the speeds of the spheres is \(2 \mathrm {~ms} ^ { - 1 }\). Find the loss of kinetic energy of the system due to the collision.