Question

1. In one inertial reference frame, an electron is observed traveling with a velocity of magnitude v in the positive x-direction, where v is 0.6c. What are the momentum and total energy of the electron in that inertial reference frame in terms of v and the rest mass of the electron? What are the speed, momentum and energy of that electron as measured in a reference frame that is traveling at a velocity of magnitude v/2 in the positive x-direction?

2. In one inertial reference frame a “photon” (quantum of light of frequency f is observed traveling in the positive x-direction. What are the momentum and total energy of the photon in terms of the frequency f? What are the speed, momentum and energy of that photon as measured in a reference frame that is traveling at a velocity of magnitude 0.8c in the positive x-direction?

3. A neutron at rest is relatively long lived but it is not a stable elementary particle, rather it eventually decays into a proton, electron and a neutrino in an average time T. How far on average will a beam of neutrons travel if they are moving at 0.8c?

Answer 1