Date:  2022-02-18

Article ID:  77597

Expressions for the energy and momentum of an object in terms of its mass and speed are usually introduced using a low-speed approximation, one that is valid only for (relative) speeds much less than the speed of light. This article introduces expressions for the energy and momentum of a single object that are valid at any speed, from zero up to the speed of light. This article also introduces Lorentz transformations.