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Homework Help: Double blocks on a incline plane

  1. Dec 23, 2012 #1
    1. The problem statement, all variables and given/known data

    See attachment (1)

    what's forces act on pulley ?
    Find direction and magnitude

    2. Relevant equations

    3. The attempt at a solution
    After we find tension in robe , See attachment (2)
    what do we work ?
    Must decomposes tension to horizontal and vertical vector and after that resultant of the two vectors ? or decomposes m1gsinθ and m2sinθ ?
    See attachment (3) and then say is that Correct solution ؟

    Attached Files:

  2. jcsd
  3. Dec 23, 2012 #2

    Simon Bridge

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    All the pulley sees is the tension in the rope.
    How many forces does the pulley see?
    What is the magnitude of each of those forces?
    Which direction does each force act?
    What is the total applied force?
  4. Dec 23, 2012 #3


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    Please give a complete statement of the problem you're working on.

    It seems that you are trying to do more than simply find the forces acting on the pulley.
  5. Dec 24, 2012 #4
    you just add the two tensions vectorially and the answer u get is the correct answer.... Tensions are the only forces acting on the pulley.

    m1gsin8 and m2gsin8 will act on the blocks, not on the pulley...
  6. Dec 24, 2012 #5
    We want to calculate forces act on pulley .
    So only tension's vectors act on pulley ?

    See attachment
    Is this correct answer ?
    Resultant vector's magnitude and direction is correct ?

    In this case F1=F2=T=28.94

    Attached Files:

    Last edited: Dec 24, 2012
  7. Dec 24, 2012 #6


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    The pulley is attached to the top of the triangular structure by bracket. This bracket exerts a reaction force upon the pulley.
  8. Dec 24, 2012 #7
    And the reaction is equal to FR but in opposite direction , right ?

    Please see Upper attachment
    Last edited: Dec 24, 2012
  9. Dec 24, 2012 #8


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    Right! Numerically, what did you get for the magnitude and direction of FR?
    Last edited: Dec 24, 2012
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