Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Volume integral question

  1. Jan 5, 2014 #1

    ppy

    User Avatar

    Hi,

    I was attempting a volume integral question out of a book. I know what the final answer is and what integral i am supposed to work out but I do not know how I am supposed to solve it. I have tried different ways such as integration by substitution and integration by parts but I do not seem to be getting anywhere.

    This is the ∫[itex]^{1}_{-1}[/itex] 4(√(1-x[itex]^{2}[/itex]))(x+1)dx The answer is 2pi.

    any help would be great thanks.
     
    Last edited by a moderator: Jan 5, 2014
  2. jcsd
  3. Jan 5, 2014 #2
    This is not a volume integral. Put x=sin u and proceed
     
  4. Jan 5, 2014 #3

    ppy

    User Avatar

    The integral started out as a triple volume integral. The part mentioned is the final part of the triple integral. I have tried x=sinu and still got nowhere. Is it a simple substitution or do I have to integrate by parts as well ?
    Thanks
     
  5. Jan 5, 2014 #4

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    hi ppy! :smile:
    davidmoore63@y's :smile: substitution does work …

    show us how far you got with it :wink:
     
  6. Jan 5, 2014 #5

    ppy

    User Avatar

    Thanks. I've got there now !
     
  7. Jan 5, 2014 #6

    Mark44

    Staff: Mentor

    The presence of the ##\sqrt{1 - x^2}## factor suggests that a trig substitution is called for, and that's the direction that davidmoore and tiny-tim are recommending.

    BTW, there are no such words in English as "intergral", "intergrate", or "intergration".
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Volume integral question
  1. Volume Question (Replies: 8)

  2. Volume integration (Replies: 1)

Loading...