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Find moment of inertia

  1. Apr 11, 2013 #1
    for part a I used the equation I=m*r^2 ---> 120(58/100)^2=40.36 kg*m^2

    b)I know how to do this using the equation K=1/2Iw^2 but my moment of inertia is incorrect.
     

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  2. jcsd
  3. Apr 11, 2013 #2

    SammyS

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    What is the moment of inertia of a uniform disk of mass, M, and radius, R ?
     
  4. Apr 11, 2013 #3
    I used the equation 1/2MR^2 and got =20.18.
    when I plugged everything into the KE equation I had 305.22 J but that is incorrect.
     
  5. Apr 11, 2013 #4

    SammyS

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    What are the units for ω ?
     
  6. Apr 11, 2013 #5
    rev/s
     
  7. Apr 11, 2013 #6

    haruspex

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    The rotation rate is given you in rev/s, but what units does it need to be in to plug it into the formula for KE?
     
  8. Apr 11, 2013 #7
    should it be rev/min or rad/s?
     
  9. Apr 11, 2013 #8
    I got it now it should be in rad/s for some reason I thought It was suppose to be rev/s.
    Thank you all!
     
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