Question: Use the position function \(s\left( t \right)=-16{{t}^{2}}+1000\) which gives the height (in feet) of an object that has fallen for t seconds from a height of 1000 ft. The velocity at time t = a seconds is given by

\[\underset{t\to a}{\mathop{\lim }}\,\frac{s\left( a \right)-s\left( t \right)}{a-t}\]

If a construction worker drops a wrench from a height of 1000 ft, when will the wrench hit the ground? At what velocity will the wrench impact the ground?