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Dynamic system question HELP

  1. Oct 21, 2012 #1
    I'm having difficulty with this question

    In the diagram, the coefficient of kinetic friction between the 2.00 kg and the 3.00 kg blocks is 0.300. The horizontal surface and the pulleys are frictionless, and the masses are released from rest.
    (a) Draw a free body diagram of each block.
    (b) Determine the acceleration of each block.
    (c) Find the tension in the strings.

    I've also been given a diagram:
    http://i1289.photobucket.com/albums/b505/homework2012/q5_zpsed497c95.jpg

    and here's my FBD: http://i1289.photobucket.com/albums/b505/homework2012/q5_zps75004cd9.jpg

    - Am i missing any forces on my FBD Diagram? If yes which ones?
    - For part b what would forces would Fnet be equal to, to find the acceleration?
    I though it would be Fnet = Fg3 + Ff
    Where Fg3 is the 10kg ball
    - How many force of friction is acting on the system? Is it just 1 between the 2kg and 3kg blocks? If not one, where are the other Ff?
     
  2. jcsd
  3. Oct 21, 2012 #2

    Doc Al

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    Staff: Mentor

    You forgot the friction acting on the bottom block.
     
  4. Oct 21, 2012 #3
    Do you also include that in the FBD diagram for the 3kg block? Because i though it was already accounted for by the 2kg block?

    What would Fnet now be equal to to find Tension?
     
  5. Oct 21, 2012 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Of course. You must include all forces acting.
    Realize that the blocks exert the friction force on each other. Newton's 3rd law.
    Apply Newton's 2nd law to each block, then solve those equations together.
     
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