Answer
See explanation
Work Step by Step
When $v\rightarrow c$ from the left, we have
$\frac{v}{c}\rightarrow !^-$
so
$1-\frac{v^2}{c^2}\rightarrow 0^+$
We determine the limit:
$\lim_{v\rightarrow c^-} m=\lim_{v\rightarrow c^-}\frac{m_0}{1-\frac{v^2}{c^2}}=\infty$
When the particle’s speed
$v$ approaches the speed of light $c$, its relativistic mass increases without bound, so it would require infinite energy to accelerate the particle to the speed of light — hence, no object with mass can reach or exceed $c$.
