[UPSC CSE 2008] Special Theory of Relativity (Q381, 20M)

A meson of rest mass $ \pi $ comes to rest and disintegrates into a muon of rest mass $ \mu $ and a neutrino of zero rest mass. Show that the kinetic energy of motion of the muon is T = \frac{(\pi - \mu)^2 c^2}{2\pi} .