Relativistic kinetic energy
= Relativistic kinetic energy
{title2=$K=(\gamma-1)mc^2$}
For a free particle of <rest mass> $m$, subtract its <rest energy> $mc^2$ from its total <energy> $\gamma mc^2$, where $\gamma$ is the <Lorentz factor>. The low-<speed> <binomial series> gives $K=mv^2/2+3mv^4/(8c^2)+O(mv^6/c^4)$, recovering classical <kinetic energy>.