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Homework Help: Cuboid stability when rotating along different axes

  1. May 6, 2012 #1
    1. The problem statement, all variables and given/known data
    If we have a cuboid like this one
    *It wont let me upload the picture or include a link but if you Google cuboid its the first picture*

    We know that the mas moment of inertia through the centroid is different for each face. So the yellow has the greatest mass moment of inertia the orange face has the second greatest moment of inertia, and the green face has the smallest moment of inertia. Now if i hold this cuboid along any two opposing faces on their center and throw it up in the air with the intent of the it spinning smoothly it will not work out so well for the orange face (the one with the second biggest mass moment of inertia). Why?

    2. Relevant equations
    Why does the box only spin nicely along two of the axes/faces but now along the other one?

    3. The attempt at a solution

    This is not really a homework question. Professor just brought it up in class and did not tell us the answer. It is weird because it is the face with the second biggest/smallest mass moment of inertia that does not spin nicely. By spinning nicely i mean that when thrown up in the air it has no stability and moves in and out of the plane very quickly. But when it is thrown along the other two it spins nicely and stays in the plane the entire time. The only thing i know is that somehow the moments are causing stability.

    It is a hard question to explain. Sorry for any confusion and please ask if any clarification is needed. Thanks in advance to anyone who helps.
  2. jcsd
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