17.2. Decay process A particle of mass M and three-dimensional momentum P decays in two particles of masses m1 and m2.

a. Use the conservation of the energy and the momentum to prove that the total energy of the first particle in the reference frame of the centre of mass is E1 = M2 +m21

−m22 2M and that E2 is obtained from the previous expression exchanging m1 with m2.

b. Show that the kinetic energy Ti of the particle i, in the same reference frame, is given by Ti = M 1− mi M

− M 2M



where M =M−m1 −m2.