Results 1 to 3 of 3

Math Help - Path Integral

  1. #1
    Newbie
    Joined
    May 2010
    Posts
    1

    Path Integral

    I'm having some issues with this path integral.
    The vector field is F=<x,-y,-z>
    The path is defined by c(t)=(sint, cost, t)
    and t is from 0 to 3pi/2

    How I have it set up, it turns out to be the integral of 2cos(t)sin(t) -t +1 from t=0 to t=3pi/2
    because I plugged the c terms into the F, then did the dot product of that with the c prime terms

    I solved this to be -cos^2(t)-((t^2)/2)+t,
    then plugged in 3pi/2

    but it was wrong
    any ideas why?


    Thanks
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by Scottyd61891 View Post
    I'm having some issues with this path integral.
    The vector field is F=<x,-y,-z>
    The path is defined by c(t)=(sint, cost, t)
    and t is from 0 to 3pi/2

    How I have it set up, it turns out to be the integral of 2cos(t)sin(t) -t +1 from t=0 to t=3pi/2 Mr F says: This is wrong. If you show all the details of your calculation the mistake(s) you made can be pointed out.

    because I plugged the c terms into the F, then did the dot product of that with the c prime terms Mr F says: Correct method but you obviously have not done it correctly. See above.

    I solved this to be -cos^2(t)-((t^2)/2)+t,
    then plugged in 3pi/2

    but it was wrong
    any ideas why?


    Thanks
    ..
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member autumn's Avatar
    Joined
    Mar 2010
    From
    unfortunalty, im stuck in hicks state. IN.
    Posts
    41
    Do you want \int \bf{F}\cdot\bf{dr}?

    \bf{F}\cdot\bf{dr}=<\sin t,-\cos t,-t>\cdot <\cos t,-\sin t,1>dt

    =(2\sin t\cos t -t)dt

    and \int (2\sin t\cos t-t)dt=\sin^2 t-t^2/2+C
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Path integral
    Posted in the Calculus Forum
    Replies: 1
    Last Post: February 8th 2010, 01:34 PM
  2. Path integral
    Posted in the Calculus Forum
    Replies: 2
    Last Post: September 10th 2009, 05:26 PM
  3. Path Integral problems
    Posted in the Calculus Forum
    Replies: 7
    Last Post: May 6th 2009, 10:56 AM
  4. Path Integral
    Posted in the Calculus Forum
    Replies: 7
    Last Post: December 11th 2008, 03:45 PM
  5. some help in Path integral
    Posted in the Calculus Forum
    Replies: 3
    Last Post: December 31st 2006, 10:38 PM

Search Tags


/mathhelpforum @mathhelpforum