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Homework Help: Blocks on a tabletop attached to a mass suspended by a pulley

  1. Feb 3, 2009 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    We have yet to go over this material, which kinda pisses me off, but I'm guessing that:

    f=ma, w=ma, g = 9.8m/s/s

    are important

    3. The attempt at a solution

    If somebody could point me in the right direction that would be very helpful. I attempted at drawing a diagram of the forces on each object, but I'm not sure where to even start.
  2. jcsd
  3. Feb 3, 2009 #2
    You want to find the mass of block C so that it moves block A but not too large that it overcomes the static friction between block A and block B I believe. So find the static friction and divide it by g to find the mass of Block C

    static friction = (coefficient of static friction) (reaction/normal force)
  4. Feb 3, 2009 #3
    So will the normal force be the mass of the two blocks times gravity?
  5. Feb 3, 2009 #4
    the normal force should be equal to the weight of Block B
  6. Feb 3, 2009 #5
    Thank you so much

    I got 3.75 kg
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