a) A particle of mass M decays into a number of particles, some of which may be photons. If one of the particles has mass m, and if the sum of the masses of all the other products is u, what is the maximum possible energy that m can have?
(b) In beta decay, a neutron decays into a proton, an electron, and a neutrino (which is essentially a photon, for the present purposes). The rest energies are En = 939.6 MeV, Ep = 938.3 MeV, Ee = 0.5 MeV, and Ev= 0. What is the maximum energy that the electron can have? The neutrino?