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

Particle is photon and it travels with the velocity equal to light in vacuum

m= 0

$m=\frac{m_{0}}{\sqrt{1-\frac{v^{2}}{c^{2}}}}$ $1-\frac{v^{2}}{c^{2}}=0$

∴ v = c