posted by Pardis .
A pion has rest energy 135MeV. It decays into two gamma rays that travel at the speed of light. A pion
moving through the lab frame at v=0.98c decays into two gamma rays of equal energies, making equal
angles θ with the direction of motion. Find the angle θ and the energies of the two gamma rays. Hint:
gamma rays are electromagnetic radiation with E=pc.