Question

A particle with total mass 6.0*m decays into a lighter particle of mass m and a photon. Assume all measurements are made in the rest frame of the initial particle. If the energy of the photon is measured to be 2.5*m, what is the gamma-factor and speed of the lighter particle?"

There are multiple right answers to this, because as written, the problem is "overconstrained." The energy of the photon can't be arbitrarily set to 2.5*m, it needs to be set to whatever makes the equations work when the initial particle has a mass of 6.0*m. In other words, I could have asked *you* to compute the energy of the photon, instead of giving it to you. your solution must be clearly presented and completely correct.

Answer 1