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Homework Help: Rotational dynamics rod- !

  1. Mar 10, 2010 #1
    rotational dynamics rod--plz help!

    1. The problem statement, all variables and given/known data
    A thin rod of length l and mass m is fixed at a far ends by a free pivot and held from rotating with a string attached at 3/4l and fixed toa ceiling. The moment of inertia of a thin rod about a far end is ml2/3

    a) what is the pivot point exerting on the rod

    The rope is cut at t =0 seconds. at t =0 seconds find:
    b) the angular acceleration of the rod.
    c) the transverse acceleration of the rod's center of mass.
    d) the transverse aceleration of point A (the far end of the rod)
    e) the force exerted by the pivot point

    picture is attached.

    Attached Files:

  2. jcsd
  3. Mar 10, 2010 #2


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    Homework Helper

    Re: rotational dynamics rod--plz help!

    You have to at least try the problem and explain your thoughts before asking for help.
  4. Mar 10, 2010 #3
    Re: rotational dynamics rod--plz help!

    First, total downward torque = upward torque.
    .5mgl + Torque of pivot point = .75mgl
    torque of pivot point = .25mgl.
    This doesnt make sense because the pivot point cant exert a torque.
    Thats all I got to...and I couldnt figure out anthing else lol
    I have all the answers, I just need to understand hwo to do it.
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