Question 159118
A ball is thrown downward from a window in a tall building. Its position in time t in seconds is s=16t^2 + 32t, where s is in feet. how long (to the nearest tenth) will it take the ball to fall 175 feet?
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s(t) = -16t^2 -32t + 175
175 is the height of the building; -32 is the throw velocity downward, 
the -16 is the velocity downward due to gravity.
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When the ball hits the ground s(t) = 0
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-16t^2 -32t + 175 = 0
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Using the quadratic formula, solve for "t":
t = [32 +- sqrt(32^2 - 4*-16*175)] / [-2*-16]
t = [32 +- sqrt(12224)]/[32]
t = [32 +- 110.56]/32
Positive answer:
t = 4.46 seconds
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Cheers,
Stan H.