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Homework Help: Moment of Inertia - Swinging arms

  1. Apr 22, 2013 #1
    momi_12.jpe

    My workings are below :

    ImageUploadedByPhysics Forums1366692390.758620.jpg

    Following the calculation of w I use v=wr where r= 3 and calculate the tangential velocity.

    It's then easy to see that a speed of 340 (Mach 1) will be attained in 128 s

    Is this correct ?
     
  2. jcsd
  3. Apr 23, 2013 #2

    haruspex

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    In your handwritten working, you've written omega instead of omega-dot, but otherwise it all looks correct.
     
  4. Apr 23, 2013 #3
    I dont understand you. Torque = Iw , correct ?
     
  5. Apr 23, 2013 #4
    No, it is

    τ = Iα

    where α is the angular acceleration
     
    Last edited: Apr 23, 2013
  6. Apr 23, 2013 #5

    haruspex

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    ... and although the OP says "I use v=wr ", what has actually been used is a = αr.
     
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