SOLUTION: I need help with this problem, i dont know how to set it up! thanks! Suppose an object is dropped from a height ho above the ground. Then its height after t seconds is given by h

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Question 178252: I need help with this problem, i dont know how to set it up! thanks!
Suppose an object is dropped from a height ho above the ground. Then its height after t seconds is given by h = -9t 2 + ho, where h is measured in feet. Use this information to solve the problem.
A ball is dropped from the top of a building 54 ft tall.
(a) How long will it take to fall half the distance to ground level?
t=____ seconds
(b) How long will it take to fall to ground level?
t=___ seconds
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
(a) If the building is 54 ft tall, then 1/2 the
distance to the ground is 54%2F2+=+27ft
The height after t seconds is 27ft
h%5B0%5D+=+54ft
h+=+-9t%5E2+%2B+h%5B0%5D
27+=+-9t%5E2+%2B+54
9t%5E2+=+54+-+27
9t%5E2+=+27
t%5E2+=+3
t+=+sqrt%283%29sec
t+=+1.732sec
(b)
Falling to ground level,
h+=+0ft (the height above ground will be 0)
and, still,h%5B0%5D+=+54ft
0+=+-9t%5E2+%2B+54
9t%5E2+=+54
t%5E2+=+6
t+=+sqrt%286%29sec
t+=+2.449sec