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Homework Help: Force and motion

  1. May 12, 2008 #1
    1. The problem statement, all variables and given/known data
    In throwing a 200-g ball, one's hand exerts a constant upward force of 9.4 N for 0.32 s. How high does the ball rise after leaving the hand? Book answer is 7.2 m.


    2. Relevant equations
    F = ma
    v = v0 + at
    y - y0 = v^2/2g

    3. The attempt at a solution

    Fup + Fdn = Fnet
    aup = Fup/m = 9.4 kg-m/s^2/200g*1000g/kg = 47 m/s^2
    v0 = at = 47m/s^2 * 0.32s = 15 m/s
    y-y0 = v0^2/2g = (15)^2/2 * 9.8 = 11.5 m
     
  2. jcsd
  3. May 12, 2008 #2
    Which should you use: aup or anet?
     
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