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Homework Help: Modified atwood machine

  1. Sep 29, 2008 #1
    1. The problem statement, all variables and given/known data

    Given in this problem is a modified Atwood Machine (block A sits on a horizontal surface with a massless rope attached which goes horizontally over a frictionless pully attached to the edge of the "cliff" which is attached downward to block B)

    W of A = 45.0 N, W of B = 25.0 N, mu = 5/9

    A 45 N cat falls asleep on box A. If box B is now set in motion, what is it's acceleration (magnitude and direction)?

    2. Relevant equations

    f[tex]_{kA}[/tex] = ([tex]\mu[/tex])n

    3. The attempt at a solution

    50N = (5/9)(90N). I then have found the net force on block B and found it to be -9.80 m/s[tex]^{2}[/tex]. The correct answer for this is 2.13 m/s[tex]^{2}[/tex] upward. What am I missing?
  2. jcsd
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