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Homework Help: Friction force on a block

  1. Mar 11, 2008 #1
    2 blocks are accelerated across a horizontal frictionless surface as shown in a diagram (block on block getting pulled by a force, larger block on bottom). TH friction forces keep the 2 blocks from sliding relatice to each other, and the two move witha same acceleration. If F= 13.00 N, m1= 3.500 kg, and m2 = 6.200 kg, what is the size of the FRICTION FORCE of the large block on the small block?

    I have no idea where to start! Please help!
  2. jcsd
  3. Mar 11, 2008 #2
    i think that only the box in the bottom is getting pulled. In that case, what is the force on the lower box? What will the acceleration be in the lower box due to this force? and finally, since the acceleration of the boxes are same, you can compute the force on the box kept above. Where does this force come from?
  4. Mar 11, 2008 #3
    it doesn't say where the force comes from but it comes from the right of the blocks horizontal to the ground.
  5. Mar 11, 2008 #4


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    Hi buys.trevor! Welcome to PF! :smile:

    HInt: draw a force diagram for the top box only.

    What have you drawn? :smile:
  6. Mar 11, 2008 #5
    Thanks to all that helped I finally figured it out after several hours hardcore studying!
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