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Homework Help: Help me proving this Kinetic Friction Coefficient

  1. Jan 6, 2013 #1
    Consider the system: A block of mass M is placed on a level table and connected to a mass m by a light string running through a pulley. If mass m is released, it will start to fall and the wooden block will be pulled across the table.

    Prove that the kinetic friction coefficient can be given by the expression: μ = m/M - a/g

    I have tried, but could only get this expression: μ= [mg - (M+m)a]/Mg . I can't get to the one outlined in the question. What am I missing?

    Thanks in advance.
  2. jcsd
  3. Jan 6, 2013 #2
    Is there any condition given that M >> m . since in that case (1 + m/M) will tend to 1, and your expression will reduce to the required expression. I am also getting the same answer as you got.
  4. Jan 6, 2013 #3


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    me too :smile:
  5. Jan 6, 2013 #4

    rude man

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    Does 4 make a greater charm than 3? :smile:
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