relativistic mass

Quick Reference

The mass of a moving body as measured by an observer in the same frame of reference as the body. According to the special theory of relativity the mass m of a body moving at speed v is given by m = m0/√(1 − v2/c2), where m0 is its rest mass and c is the speed of light. The relativistic mass therefore only differs significantly from the rest mass if its speed is a substantial fraction of the speed of light. If v = c/2, for example, the relativistic mass is 15% greater than the rest mass.

Subjects: Physics.

Reference entries