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

Ray d inverno problem 11.5

  1. Jun 17, 2013 #1
    i have a doubt in this problem ; is correct say that :

    L_m(y) = L(y) + δL(y) = L(y + δy)= L(y) + δy(∂L/∂y) ??

    where L_m is modified Lagrangian
    and y is dynamical variables.

    I get answer but i have it doubt.
  2. jcsd
  3. Jul 12, 2013 #2


    User Avatar
    Gold Member

    Hi Duvan_Br,

    I think you need to go back to the original Euler-Lagrange equations (7.35) and work forward from there to find δ(L1+L2)/δyA = 0 and
    δ(L1L2)/δyA = 0. (The '= 0' bit is very important!)


Share this great discussion with others via Reddit, Google+, Twitter, or Facebook