In a gamma decay process, the internal energy of a nucleus of mass M decreases, a gamma photon of energy E and linear momentum E/c is emitted and the nucleus recoils. Find the decrease in internal energy.

Explanation

K.E. of Nucleus `=(1/2)mv^2`
`=(1/2)m(E/mc)^2=E^2/(2mc^2)`
Energy emitted by Gamma photon=E
`Decrease in interN/Al energy `=E+E^2/(2mc^2)`