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Homework Help: Advice on volume of solids NOT of revolution?

  1. Dec 29, 2006 #1
    Anyone have any advice for finding volumes of solids that are not solids of revolution? I have a much more difficult time starting these kinds of problems compared to revolving ones.
     
  2. jcsd
  3. Dec 29, 2006 #2

    radou

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    I'm not sure anyone can help you unless you become a bit more specific.
     
  4. Dec 29, 2006 #3
    I mean general things to do or whatever to start these kinds of problems. And also what would a typical cross section be like? Whereas when using washer method/shell method the solid is revolved so cross sections are circular, do the cross sections for these problems depend entirely on the question?

    for example:
    A hole of radius r is bored through a cylinder of radius R > r at right angles to the axis of the cylinder. Set up an integral (no need to evaluate) for the volume cut out.
     
  5. Dec 29, 2006 #4

    radou

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    If you know the function which defines the cross section, then you can calculate the integral. You may want to do some google-ing on Cavalieri solids. I hope I was at least a bit helpful. :wink:
     
  6. Dec 29, 2006 #5
    say you are integrating a cube, then the area of a typical cross section would be l*w. for a cone it is pi*r^2 etc..it really depends on what kind of solids you are trying to find the volume of. But a cross section is just an infinitely thin slice out of the solid.
     
  7. Dec 30, 2006 #6

    HallsofIvy

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    There is no general method for finding the volume of an arbitrary 3 dimensional solid.
     
  8. Dec 31, 2006 #7

    Gib Z

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    Yes there is, putting it in water :D
     
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