According to the Theory of Relativity, the mass $m$ of a particle depends on its velocity $v .$ That is
$$m=\frac{m_{o}}{\sqrt{1-\left(v^{2} / c^{2}\right)}}$$
where $m_{o}$ is the mass when the particle is at rest and $c$ is the speed of light. Find the limit of the mass, $m,$ as $v$ approaches $c^{-}$ .