Question

The sky diver was free falling for how many seconds?

Answer 1

Given

$s(t)=16t^2$

Since the skydiver fell 4800ft, we need to set s(t)=4800 and solve for t, as shown below

$\begin{gathered} s(t)=4800 \\ \Rightarrow16t^2=4800 \end{gathered}$

Solve for t, as follows,

$\begin{gathered} \Rightarrow t^2=\frac{4800}{16}=300 \\ \Rightarrow t=\pm\sqrt{300}=\pm\sqrt{100*3}=\pm10\sqrt{3} \\ \Rightarrow t=\pm10\sqrt{3} \end{gathered}$

However, a negative time would indicate that the skydiver was falling before jumping from the plane, which is impossible.

Therefore, the only valid answer is 10sqrt(3).

The answer is 10sqrt(3)