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!

Minimisation Problem (Euler-Lagrange equation)

  1. May 24, 2016 #1
    1. The problem statement, all variables and given/known data
    http://i.imgur.com/BV5gR8q.png

    2. Relevant equations
    d/dx ∂F/∂y'=∂F/∂y

    3. The attempt at a solution
    I have no problem with the first bit, but the second bit is where I get stuck. Since the question says the speed is proportional to distance, I have taken v(x)=cx where c is some constant of proportionality, then tried to proceed with solving the EL equation, however I end up with everything just being equal to 0 so I'm not sure how to proceed.

    http://i.imgur.com/hDNPyG7.jpg
     
  2. jcsd
  3. May 24, 2016 #2
    Hi Plaetean:

    I think you forgot that y' is a function of x.

    Your (d/dx) ∂F/dy' does not include any dy'/dx = y''.

    Hope this helps.
    Regards,
    Buzz
     
  4. May 27, 2016 #3

    rude man

    User Avatar
    Homework Helper
    Gold Member

    What does your Euler-Lagrange equation boil down to if F is not a function of y?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Minimisation Problem (Euler-Lagrange equation)
Loading...