A π0 meson (rest-mass energy 135 MeV) is moving with velocity 0.8c in the laboratory rest frame when it decays into two photons γ1 and γ2. In the π0 rest frame, γ1 is emitted forward and γ2 is emitted backward relative to the direction of flight. The velocity of γ2 in the laboratory rest frame is
Photon moves with the speed of light → B, C, E are FALSE.
Since γ2 is emitted backward, the velocity of γ2 is −1.0c