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Homework Help: Moment of Inertia lab equation

  1. May 2, 2012 #1
    I'm working on a lab where I have to go into some detail about moment of inertia. I understand the concept and everything but am a little confused by the equation that I found on wikipedia.
    I've seen only two equations for this: momentum=torque divided by angular acceleration and
    one specifically for a disk: I=.5MR2

    On wikipedia I they have the equation: T=ml2[itex]\omega[/itex]2
    Wikipedia makes sense to me because I understand that as radius decreases momentum decreases at constant angular velocity. Neutron stars for instance maintain similar inertia at reduced radius but much higher angular velocity.

    Are all 3 ways true?
  2. jcsd
  3. May 4, 2012 #2
    I'm assuming you meant that moment of inertia = torque divided by angular acceleration, because what you have there isn't true (just look at the units.)

    I agree with this.

    I'm assuming that you're referring to this page. You'll note that [itex]T[/itex] is in fact the kinetic energy of the object and not the moment of inertia. You may have been confused just because [itex]T[/itex] is similar to the symbol for torque, [itex]\tau[/itex].
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