energy. If a photon has momentum can it not also have kinetic energy? The fact that the photon has momentum but no mass can be understood within the framework of relativity. In general, for a particle of rest mass mo, the momentum is e-m 24 (3) Therefor, for the photon with zero rest mass E hy h (4)energy. If a photon has momentum can it not also have kinetic energy? The fact that the photon has momentum but no mass can be understood within the framework of relativity. In general, for a particle of rest mass m0 , the momentum is Therefor, for the photon with zero rest mass