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Homework Help: Moment of inertia - Disc

  1. Oct 14, 2012 #1
    Consider a solid disk made of aluminum with a central hole as shown in the figure - can't include...don't believe it's necessary. The external and internal diameters are found to be 13 inches and 0.6 inches. The disk is 0.5 inch thick. The density of aluminum is 2.70 g/cm3. Question:
    Calculate the moment of inertia of this disk for rotations about its axle, in kg m2.

    I have no idea how to determine the mass of a disk. I believe to determine the moment of inertia I use the formula Mxr^2

    Formulas would be VERY much appreciated. I have several more problems on this pre-lab that are similar to this question. Thank you very much!
  2. jcsd
  3. Oct 14, 2012 #2
    Think of 2.7g/cm3 as a formula to find mass if you have volume in cm3. Therefore maybe start with finding the volume of the disk.
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