Question

A neutron having kinetic energy 12.5 eV collides with a hydrogen atom at rest. Neglect the difference in mass between the neutron and the hydrogen atom and assume that the neutron does not leave its line of motion. Find the possible kinetic energies of the neutron after the event.

Answer 1

In one dimensional elastic collision of two bodies of equal masses, the initial velocities of bodies are interchnged after collision.

$\therefore$ Velocity of the neutron after collision is zero. Hence, it has zero energy.