
457Theory of Special Relativity
It is now easy to see that a material body cannot have a velocity greater than the velocity of
light. If we try to accelerate the body, as its velocity approaches the velocity of light, its mass
becomes larger and larger as it becomes increasingly more difcult to accelerate it further. In
fact, because the mass m becomes innite when v = c, we can never accelerate the body up to the
speed of light.
Example 13.3: Variation of Mass with Velocity
For the sake of simplicity, we shall consider the case of a central inelastic collision between two
particles of equal mass whose velocities, as viewed in the S′ system, are ...