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Homework Help: Torque with pulleys and bucket of water

  1. Oct 31, 2006 #1
    Imagine a frictionless pulley (a solid cylinder) of unknown mass M and radius r = 0.41 m is used to draw water from a well. A bucket of mass m = 1.53 kg is attached to a cord wrapped around the cylinder. A bucket starts from rest at the top of the well and falls for t = 2.04 s before hitting the water h = 2.87 m below the top of the well. Neglect the mass of the cord.

    t = F*R
    t=(1.53*9.81) * .41

    t = 6.15 Nm??
     
  2. jcsd
  3. Oct 31, 2006 #2

    Doc Al

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    Staff: Mentor

    What's the question? (Find the unknown mass of the pulley?)

    Hint: What directly exerts the torque on the cylinder is the tension in the rope, not the weight of the bucket.
     
  4. Oct 31, 2006 #3
    sorry, the question is asking what the torque is; i cant seem to figure it out for some reason?
     
  5. Oct 31, 2006 #4

    Doc Al

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    Staff: Mentor

    Find the tension in the rope.

    Hints: Analyze the forces acting on the bucket. Apply Newton's 2nd law. (What's the acceleration of the bucket?)
     
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