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Forces doing work

  1. Mar 4, 2008 #1
    1. The problem statement, all variables and given/known data
    A box is being pulled up a rough incline by a rope connected to a pulley as shown below. The arrows indicate the direction of motion of the blocks. How many forces are doing work on the box?
    (view attachement)

    2. Relevant equations

    different forces must be taken into account

    3. The attempt at a solution

    ok so theres the normal force, force, friction?

    Attached Files:

  2. jcsd
  3. Mar 4, 2008 #2

    Doc Al

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    Staff: Mentor

    First figure out how many forces act on the box. In what direction do they act?

    Then figure out which of those forces do work on the box.

    Hint: I count 4 forces acting on the box.
  4. Mar 4, 2008 #3
    yea...i guessed that there were four forces cuz i was looking over another problem in my book that resembled this problem but i dont understand what the forces are..
    but then i checked the answer for this problem just now..and the answer is three froces?!?!
  5. Mar 4, 2008 #4

    Doc Al

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    Staff: Mentor

    I advise you to first understand how to identify the forces that act on the box before you worry about which of them are doing work. Start listing them and specify which way they point.
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