1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Moment of Inertia Questions

  1. Oct 8, 2004 #1
    **The problem and solution is attached as moment of inertia.**
    **The equations for moment of inertia of known homogeneous solids is also attached**

    I'm having some trouble grasping this concept. I hope someone can help clarify some things for me.

    Looking at the problem I realized I would have to use the parallel axis theorem, but after that the trouble begins. (I = Ig + m*d^2)

    "Deterimine the wheel's M of I about an axis perpendicular to the page and passing thru pt A."

    What does this mean? What is it saying?

    And a related question to the above: Why when calculating M of I for the thin ring (Homogeneous solids jpeg) do you use Izz = m*r^2 instead of Ixx or Iyy? Same question for the slender rod. How do you know which one to use?

    I realize I've said a lot, but I hope someone can give me some pointers.

    Attached Files:

  2. jcsd
  3. Oct 8, 2004 #2
    Have you identified what the axis passing through A looks like?

    The axis A appears parallel to the z axis judging from the orientation of the second picture so yes you are correct. If you look at the orienation of the rods they are perpendicular to the A axis so judging from the second picture again you should use the y M of I.

    My personal opinion is that for simple objects like that it is easier to derive the M of I so perhaps just remembering that the M of I is in integral form (r^2dm)
    Last edited by a moderator: Oct 8, 2004
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Moment of Inertia Questions