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Homework Help: Moment of inertia

  1. Nov 29, 2008 #1
    1. The problem statement, all variables and given/known data
    see problem 8 attachment

    2. Relevant equations
    see problem 8 attempt attachment

    3. The attempt at a solution
    see problem 8 attempt attachment
    I think I have solved the problem correctly and through my method I determine the moment of inertia to be 4.3 kg*m^2. However I'm not sure if the equations I used to find velocity and acceleration are valid in this situation.

    Attached Files:

  2. jcsd
  3. Nov 30, 2008 #2


    User Avatar
    Homework Helper

    Hi jimbo71,

    I think the assumption you have made (that is not necessarily true) is that the wheel is a uniform disk.

    Once you found the linear acceleration of 0.75 m/s2, you can directly find the angular acceleration alpha from [itex]a=r\alpha[/itex].

    Then you can use the torque equation like you did, but there is no need try to write out an expression for I, since I is what you want. Just use:

    \tau = I\alpha

    and solve for I.
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