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Homework Help: Finding the moment of inertia for a hollow cylinder

  1. Apr 5, 2004 #1
    I need help finding the moment of inertia for a hollow cylinder with a closed bottom (like a glass of water). My strategy is to add the moments of inertia of the cylinder and the disk but I only have the total mass of the whole object. Is there a way to find the mass of each part or is there another approach to this problem?
  2. jcsd
  3. Apr 5, 2004 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    Just sum the mass as an integral as follows.

    [tex]I=\int r^2 dm [/tex]
  4. Apr 6, 2004 #3

    Doc Al

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    Staff: Mentor

    If the thickness is uniform then you can find the masses of the cylinder and bottom by comparing their relative areas. The surface area of the cylinder is Lx2πr; the area of the bottom is πr2.
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