A ball is dropped from the top of a 335-foot
building.
How many seconds will it take to hit the
ground if the height is given by
h = −16t
2 + s,
where s is the initial height?
Answer in units of sec.

Question

A ball is dropped from the top of a 335-foot
building.
How many seconds will it take to hit the
ground if the height is given by
h = −16t
2 + s,
where s is the initial height?
Answer in units of sec.

mathmate · Answer

$h = −16t^2 + s,$

Assume y=0 at ground level, then the top of a 335-foot building is at s=335 feet.
Apply given equation, h=0 at the end of the free-fall, so
0=335-16t^2
solve for t (in seconds).