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Math Help - antiderivative world problem

  1. #1
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    antiderivative world problem

    A stone is dropped from the top of a 450 m tower. (Acceleration due to gravity is -9.8 m/s2. Ignore air resistance. Give your answers correct to two decimal places.)

    (a) Find the distance of the stone above ground level at time t.
    s(t)= 450 - \frac{9.81t^2}{2}

    (b) How long does it take the stone to reach the ground?

    0 = 450 - \frac{9.81t^2}{2}

    t = \sqrt\frac{(2 * 450)}{ 9.81}
    =  9.58 sec.

    (c) With what speed does it strike the ground? This is the part I keep getting wrong.

    <br />
v(t)=-9.8t
    = -9.8(9.58)
    = -93.97
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  2. #2
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    Quote Originally Posted by hazecraze View Post
    A stone is dropped from the top of a 450 m tower. (Acceleration due to gravity is -9.8 m/s2. Ignore air resistance. Give your answers correct to two decimal places.)

    (a) Find the distance of the stone above ground level at time t.
    s(t)= 450 - \frac{9.81t^2}{2}

    (b) How long does it take the stone to reach the ground?

    0 = 450 - \frac{9.81t^2}{2}

    t = \sqrt\frac{(2 * 450)}{ 9.81}
    =  9.58 sec.

    (c) With what speed does it strike the ground? This is the part I keep getting wrong.

    <br />
v(t)=-9.8t
    = -9.8(9.58)
    = -93.97
    speed is a scalar > 0
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