In the above problem loss of `KE` during collision is

In the above problem the total KE before collision is

Two equal spheres B and C , each of mass m , are in contact on a smooth horizontal table. A third sphere A of same size as that of B or C but mass m//2 impinges symmetrically on them with a velocity u and is itself brought to rest. The loss of KE during collision is

A ball released from a height of 20m, hits the ground and rebounds to a height of 16m. The percentage loss of energy during collision is

Prove that there is a loss of KE during one dimensional inelastic collision.