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Homework Help: Force in a dynamics of rotation problem?

  1. Oct 9, 2005 #1

    A bucket of water of mass 15.0 kg is suspended by a rope wrapped around a windlass, that is a solid cylinder with diameter 0.290 m with mass 12.4 kg. The cylinder pivots on a frictionless axle through its center. The bucket is released from rest at the top of a well and falls a distance 11.0 m to the water. You can ignore the weight of the rope.

    The fourth and final part of the question is "While the bucket is falling, what is the force exerted on the cylinder by the axle?"

    Quite frankly, I don't really understand this question. When I drew the free body diagram, I'm inclined to say the answer is (12.4)(9.80).

    Is this asking for the normal force?
  2. jcsd
  3. Oct 9, 2005 #2
    Never mind, I got it.

    I forgot that it's just (12.4)(9.80) + T, where T is 43.0 and was asked for in the first part of the question.
  4. Oct 10, 2005 #3


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    Last edited: Oct 10, 2005
  5. Jun 3, 2006 #4
    I had trouble with the question intially also, because of the wording, but it makes sense: there are two forces that act on the cylinder while the bucket is falling, its own weight, and the Tension of the bucket.

    By adding these, you get the total force that's acting on the cylinder.

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