Use the position function $s(t)=-4\mathrm{.}9t^{2}600,$ which gives the height $($in meters$)$ of an object that has fallen for t seconds from a height of $600$ meters. The velocity st time $f=s$ seconds is glven by the following.

$\underset{ta}{lim}\frac{s(a)-s(t)}{a-t}$

Find the velocity of the object $($in mVs $)$ when $t=2.($Round your answer to one decimal place.$)$

$\frac{m}{s}$