Question

Use the position function s(t)=-16t^2+vOt+sO
vO=initial velocity sO=initial position t=time
to answer the following question.
You throw a ball straight up from a rooftop 152 feet high with an initial velocity of 64 feet per second. During which time period will the ball's height exceed that of the rooftop?

ANSWER: Between and seconds.

Answer 1

insert values:
152=-16t^2+64t+152
0=16t(4-t)

solutions: t=0 and t=4

so when t=0 or 4 the height of the ball is 154. since you're throwing the ball upwards, at t=0 the ball is above 154ft, at t=4 the ball is below 154ft.

Answer 2

Okay thanks!