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Homework Help: Vertical Motion under Gravity Q)

  1. Jun 6, 2007 #1
    1. The problem statement, all variables and given/known data
    Apologies for so many posts, however this is the last question.

    A stone his thrown vertically upwards with speed 16m/s from point h meters above the ground. The stone hits the ground 4s later.
    Find the value of h.

    3. The attempt at a solution
    I really haven't a clue on how to start this question, I haven't really encoutered this before, and would end up doing my own sledgehammer way.
    But otherwise, can someone people give hints on how to solve this, I know all the kinematic equations, its just this situation confuses me cause of h.

    Thanks in advance.
  2. jcsd
  3. Jun 6, 2007 #2
    delta y = (voy)t - 4.9t^2

    when the stone hits the ground, its vertical displacement will be the opposite of its initial height ...

    delta y = -h

    -h = 16t - 4.9t^2

    sub in t = 4 ... h = ?
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