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Homework Help: Forces problem with jumping

  1. Nov 8, 2008 #1
    1. The problem statement, all variables and given/known data
    Standing position: 100cm
    Lowered hip position: 77cm
    Peak height: 140cm

    Question "Use the peak height of the jump and the standing hip position to calculate the initial velocity of the jumper just after he left the ground"

    2. Relevant equations

    3. The attempt at a solution
    Unknown - I only know equations that require time. I know no time measurement in this problem.

    The problem is a jumping problem. The variable above, in order, are:
    1. Standing tall - from the floor to the hip
    2. Crouched down to jump - from the floor to the hip
    3. In mid-air at the peak of the jump - from the floor to the hip.

    These were measured using a 2-meter stick.
  2. jcsd
  3. Nov 8, 2008 #2
    You need to use the force formulas:

    PE spring = 1/2kx^2
    KE = 1/2mv^2
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