A neutron moving with a speed v strikes a hydrogen atom in ground state moving towards it with the same speed. Find the minimum speed to the neutron for which inelastic (completely or partially) collision may take place. The mass of neutron = mass of hydrogen = 1.67 × 10–27 kg.

For inelastic collision to take place between neutron and hydrogen of same mass the sum of initial kinetic energy should be greater than or equal to amount of energy absorbed for change in transition to first exited state.


Energy for first exited state


Sum of kinetic energy= K.E of neutron+ K.E of hydrogen atom


(as both has same velocity)



So for minimum speed




m/s


m/s


1