Question

A particle which has zero rest mass and non-zero energy and momentum must travel with a speed

(1) equal to c, the speed of light in vacuum
(2) greater than c
(3) less than c
(4) tending to infinity

Answer 1

The particle with zero mass Non-zero energy and momentum must travel with the speed of light in vacuum

• Photon particles have no mass

• Photon particles have Non-zero energy and momentum.so the particles are photons

• For photons ,m₀ = 0

         m=m₀/√1-(v²/c²)

        v = c

• Photons travel with the speed of light equal to c in vacuum