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Real world problem

  1. Mar 4, 2008 #1
    I need to roll a 9000lb roll across the ground. It is 4.5 feet in diameter, and is 115 feet long. I am attaching the bold ends to apply torque to move it. I don't need to move it that fast. How much Torque would I have to apply to each end to roll this across a flat floor. Assume that all torque applied is used to roll the drum and nothing else slips or moves. I have a number, I am trying to determine if it is correct. I am coming up with roughly 158 lb/ft per end. Any help is greatly appreciated.

    Steve Campbell
  2. jcsd
  3. Mar 4, 2008 #2


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    It's the basic

    [tex]\Sigma{T} = I \alpha[/tex]

    Set your desired acceleration and calculate the required torque from that. That will be a higher number than the torque required to simply overcome friction to maintain a constant speed.
  4. Mar 10, 2008 #3


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    If he assumes constant velocity, then there is no acceleration though, and theoretically the needed torque would be zero. However, one of the main friction forces is from the body deforming.

    I remember back from machine design that there are formulas to calculate deflection of spheres and cylinders based on various material parameters. But, even based on a known deformation, I'm not quite sure how to convert that to a friction coefficient.
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