A ball is thrown from an initial height of 3 feet with an initial upward velocity of 21 ft/s. The ball height h (in feet) after t seconds is

Question

A ball is thrown from an initial height of 3 feet with an initial upward velocity of 21 ft/s. The ball height h (in feet) after t seconds is given by the following. h=3+21t-16t^2 find all values of t for which the balls height is 9 feet.

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Vân Khánh 5 years 2021-08-12T21:30:21+00:00 1 Answers 392 views 0

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  1. kimchi2
    0
    2021-08-12T21:32:05+00:00
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    Answer:

    Step-by-step explanation:

    The position equation is given as

    s(t)=-16t^2+21t+3 and we are looking for the times when the position of the ball is 9 feet. That means that we simply plug in a 9 for s(t) and factor to solve for t:

    9=-16t^2+2t+3 and

    0=-16t^2+21t-6 and this is what we factor to find t:

    t = .42 sec and then again on its way back down at t = .89 sec

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