1. A 100 MeV particle decays into two particles. one of these two particles has a mass of 10 MeV and a speed of 3/5.
a) what are the mass and speed (in the initial particle rest frame) of the second particle?
b) in the frame of the 10 MeV particle, what was the inital particle's speed?
c) in the frame of the 10 MeV particle, what is the speed of the other final particle?