algebra

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The height above ground of a rock dropped from a bridge can be found using the formula h(t) = 9.8tsquared + 100, where t represents the number of seconds.
What is the height of the rock after 3 seconds?
How long will it take the rock to hit the bottom?

  • algebra -

    Your equation should read
    h(t) = -9.8t^2 + 100

    when t = 3
    h(3) = -9.8(9) + 100
    = 11.8

    it will be 11.8 m above the ground

    how long to hit ground ??
    when h(t) = 0
    0 = -9.8t^2 + 100
    9.8t^2 = 100
    t^2 = 100/9.8 = 10.204..
    t = √10.204.. = appr 3.2 seconds

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