Calculus Gravity Question?

Hi, i have a practice problem i need help with.

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  • Alan
    Lv 7
    1 month ago

    your first equation is position .

    d(t) = 4.9t^2

    but you want velocity = 98 m/s

    v(t) = 9.8t

    9.8t = 98

    t = 98/9.8 = 10 seconds

    now , plug 10 seconds back into your distance equation

    d(10 seconds) = 4.9(10)^2 = 4.9*100 = 490 meters

    so you need to be 490 meters high to reach

    a speed of 98 m/s when you hit the ground

  • nbsale
    Lv 6
    1 month ago

    The speed will be the derivative of the distance, so at time t the speed is

    v(t) = d'(t) = 9.8t.

    That fits with the physics, because the acceleration due to gravity is 9.8m/s^2.

    Now find t such that v(t) = 98, and plug that value into d(t).

    • nbsale
      Lv 6
      1 month agoReport

      "I rearranged it so 98=4.9t^2," No, that's not what I said to do. Read it carefully.

  • 1 month ago

    You need to contact YOUR teacher

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