1. (a) A proton is moving at a speed much less than the speed of light. It has kinetic energy K1 and momentum p1. If the momentum of the proton is doubled, so p2=2p1, how is its new kinetic energy K2 related to K1?
2. (b) A photon with energy E1 has momentum p1. If another photon has momentum p2 that is twice p1, how is the energy E2 of the second photon related to E1?