Question

You drop a ball from a set of bleachers that is 64 feet above the ground.

How long will it take the ball to hit the ground?
(Use the vertical motion model h = 1672 + Wt+s where height is measured in feet
and time is measured in seconds)

Answer 1

2 seconds

Explanation:

Filling in the given values in the appropriate ballistic motion formula, we have ...

`h(t)=-16t^2+v_0t+s_0\qquad\text{initial vertical velocity $v_0$, and initial height $s_0$}\\\\h(t)=-16t^2+64\qquad\text{$v_0=0$ and $s_0=64$}\\\\t^2=4\qquad\text{divide by 16, add $t^2$}\\\\t=2\qquad\text{take the positive square root}`

It will take the ball 2 seconds to hit the ground.