Work, Energy, Power and Collision — JEE physics STD 12 Science — Question

(c) When two bodies of same mass undergo an elastic collision, theirvelocitiesgetinterchanged after collision. Water and heavy water are hydrogenic materials containing protons having approximately the same mass as that of a neutron. When fast moving neutrons collide with protons, the neutrons come to rest and protons move with the velocity of that of neutrons.