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!

Double Integral

  1. Nov 28, 2003 #1
    OK OK I know Double Integral is from Multivar Calculus,

    I was just wondering what we use it for... I heard is good for volumes, but can't yhou also find volumes by just 1 integral?

    And also, aside from integrals in Multivar calc, what else are useful?

    I want to get a intro to it, can any one give a lecture or link to a intro page? Thanks.
  2. jcsd
  3. Nov 28, 2003 #2
    While you're correct that a volume, or area, can be obtained from a single integral, the more general double integral is better suited to more complex problems.

    It allows you to integrate a function over an area, while the triple integral does the same over a volume. There are really an infinite number of applications, but a good one is finding mass from density.

    Using the double integral one can take the density function and integrate it over an area, thus finding the mass of a lamina. With a triple integral, you can find the mass of any relatively simple solid region, for which a density function exists.

    If you'd like to see more about this, I've had good luck here:
  4. Nov 28, 2003 #3
    No, you cannot calculate volumes with just one integral, if you are speaking of the volume of an arbitrary-shaped region. (Highly symmetric regions can be reduced to single integrals, because you can implicitly pull out some of the integrals as constants.)
  5. Nov 29, 2003 #4
    I was referring to the method of finding volume-using areas of revolution or concentric shells. Which of course does only apply to highly symmetric shapes. I assume this is what you're referring to.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Double Integral
  1. A double integral (Replies: 1)

  2. Double Integrals (Replies: 0)

  3. Double integral (Replies: 6)