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Homework Help: FB Diagram problem

  1. Jan 6, 2009 #1
    1. The problem statement, all variables and given/known data


    2. Relevant equations

    Is my sketch(illustration) and fbd correct? Is T(orange) = T (blue)?

    3. The attempt at a solution
  2. jcsd
  3. Jan 6, 2009 #2


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    Yes, for the bucket. The fbd of the pulley is not correct, your forces are not in the right direction, and there is an additional force on the pulley not shown at the point where it is supported. But don't worry about the fbd of the pulley, since you don't need that one.
    Yes, as long as the pulley is frictionless and massless.
  4. Jan 6, 2009 #3
    can you give me the correct fbd for the pulley? I just wanna know.
  5. Jan 6, 2009 #4
    I think fbd: (pulley) should be fbd: (hand)? is it correct?
  6. Jan 7, 2009 #5
    As Jay mentioned, you don't need the force diagram for the pulley since all it does in this question is change the direction of a force. In this case, a force F causes a tension T in the rope, which is redirected to pull the block upwards.

    Perhaps what you need is a force body diagram for the hand/thing that provides the force F.
  7. Jan 7, 2009 #6


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    jaseh86 is correct. If you want to know the free body diagram of the pulley,which must be anchored to a table or such, you have T acting to the right, and T acting down (the rope tension), and for equilibrium, you must have the table supporting reaction force, R, acting up and to the left at a 45 degree angle thru the center of the pulley (R= T/cos45 = 1.414T). But don't fool with it.
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