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Calc-Motion under gravity

  1. Nov 18, 2003 #1
    Someone plz help me with these problems below...I'm so confused...
    Plz show me clearly how to begin...too...I'm not good with mixing calc and physics... Thanks very very much.
    1) With what velocity must an arrow be shot upward in order to fall back to its starting point 10 seconds later? How high will it rise?
    2)A woman standing on a bridge whrows a stone straight up. Exactly 5 seconds later the stone passes the woman on the way down, and 1 second after that it hits the water below. Find the initial velocity of the stone and the height of the bridge above the water.
    3)How much time does a train traveling 144km/h take to stop if it ahs a constant negative acceleration of 4 m/s^2? How far does the train travel in this time?
  2. jcsd
  3. Nov 18, 2003 #2


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    Staff Emeritus
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    Gold Member

    Are you familiar with these equations?

    [tex]v(t) = v_0 + a t[/tex]

    [tex]x(t) = x_0 + v_0 t + \frac{1}{2} a t^2[/tex]

    - Warren
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