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Two pulleys system (please check my work)

  1. Oct 14, 2008 #1
    1. The problem statement, all variables and given/known data
    Find the acceleration of the system
    http://img266.imageshack.us/img266/4904/2pulleyszw9.jpg [Broken]
    The rope is massless
    The mobile pulley is not massless, it weighs 20 grams.
    Find the accelereation of the system

    2. Relevant equations
    g = 9.8

    3. The attempt at a solution

    for W1:
    Fy = 2T-W1 = ma
    2T-(500+20)*g = (500+20)*a
    2T-520g = 520a (equation 1)

    for W2:
    Fy = W2-T=ma
    T = 300(g-a) (equation 2)

    equation 2 in equation 1 gives
    a = 1,43

    Is it correct?
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Oct 14, 2008 #2
    i don't think it's correct.. i think there is an error in the tensions, but i don't see
    Last edited: Oct 14, 2008
  4. Oct 16, 2008 #3
    can someone help me?
    I really want to know how to do this =(
  5. Oct 16, 2008 #4
    The equations seem to be OK. The solution is not. Try to solve again the two equations.
    If you show how you solve them I can try to find the mistake, if any.
    Be careful with the units. If you want to get the tension in newtons, the mass should be in kg.
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