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Homework Help: Finding a max angular acceleration

  1. Nov 4, 2008 #1
    Given is a 6' long 40 lb bar hung horizontally by a pin O at its end. It is released from its horizontal position and hits a stopper after reaching a 30 degree angle with the horizontal position at which it started. I am asked to find the value x for which the angular velocity is a maximum and also the corresponding angular acceleration alpha


    Sum of the torques about O=I(alpha)
    a(t)=r*alpha


    I honestly do not know where to start with this one. do I start by summing moments about O?
    Thanks in advance for any help.
     
  2. jcsd
  3. Nov 5, 2008 #2

    tiny-tim

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    Hi jhayes25! :smile:

    (what's x? :confused:)

    Hint: use the moment of inertia of the bar about its end, and net torque = rate of change of angular momentum. :wink:
     
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