SOLUTION: A ball is dropped from the top of a 576 ft. building. Its height h(t) at time t seconds is given by h(t)=-16t^2+576. Find the height of the ball after 2 seconds: I know this is

Algebra ->  Customizable Word Problem Solvers  -> Evaluation -> SOLUTION: A ball is dropped from the top of a 576 ft. building. Its height h(t) at time t seconds is given by h(t)=-16t^2+576. Find the height of the ball after 2 seconds: I know this is       Log On

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Question 517015: A ball is dropped from the top of a 576 ft. building. Its height h(t) at time t seconds is given by h(t)=-16t^2+576.
Find the height of the ball after 2 seconds:
I know this is 512 ft.
The next part...Determine how long it takes the ball to hit the ground:
I came up with 36 seconds but it was wrong and I can't figure it out.

Answer by jessica43(140) About Me  (Show Source):
You can put this solution on YOUR website!
To solve this problem, you need to solve for t when h = 0. So:
h = -16t^2 + 576
0 = -16t^2 + 576 (subtract 576 from each side)
-576 = -16t^2 (divide each side by -16)
36 = t^2 (take the square root of each side)
6 = t
So it will take the ball 6 secs to hit the ground.