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What is this formula for?/What is it called?

  1. Jun 1, 2014 #1
    I have a formula, S*r=1/2*m*r^2*a/r

    The problem is that it is unlabeled, and I am not 100% sure what this is supposed to be for. As near as I can tell, it is for something with inertia, and involving tension on a wire coiled around a cylinder. Is this correct? Does anyone know if this is simply a derived equation for a specific problem, or a general use equation? Thank you.
  2. jcsd
  3. Jun 1, 2014 #2


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    Staff: Mentor

    r cancels out.
  4. Jun 1, 2014 #3
    I know, but this is a formula that was supplied for a problem, and I am attempting to figure out what everything is. I think I have it narrowed down that S*r is supposed to be torque, and everything else on the right is supposed to represent inertia times the angular momentum, but I am not sure.
  5. Jun 4, 2014 #4
    You are on the right track, I see it as torque = (moment of inertia) x angular acceleration.
    S is force, r is radius, 1/2 m rsq is moment of inertia, and a is linear acceleration, a/r is angular acceleration.
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