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!

Help with the Euler-Lagrange formula for a geodesic

  1. Oct 20, 2009 #1
    1. The problem statement, all variables and given/known data

    The metric is:

    ds[tex]^{2}[/tex] = y[tex]^{2}[/tex](dx[tex]^{2}[/tex] + dy[tex]^{2}[/tex])

    I have to find the equation relating x and y along a geodesic.


    3. The attempt at a solution

    ds = [tex]\sqrt{ydx^{2} + ydy^{2}}[/tex] - is this right?

    ds = [tex]\sqrt{y + yy'^{2}}[/tex] dx

    F = [tex]\sqrt{y + yy'^{2}}[/tex]

    So then I apply the Euler-Lagrange equation

    dF/dy - d/dx[dF/dy'] = 0


    Now I'm stuck, please help.
     
  2. jcsd
  3. Oct 20, 2009 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    It's a y^2 inside the square root, isn't it? Not a y.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Help with the Euler-Lagrange formula for a geodesic
  1. Euler's formula (Replies: 1)

  2. Euler's Formula (Replies: 2)

  3. Euler's Formula help (Replies: 4)

  4. Euler's formula. (Replies: 1)

Loading...