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Expressing A Quantity In Polar Coordinates?

  1. Dec 3, 2015 #1
    1. The problem statement, all variables and given/known data
    Express the quantity ∂2/∂x2+∂2/∂y2 in polar coordinates.

    2. Relevant equations
    x=ρcosφ
    y=ρsinφ
    ρ=sqrt(x2+y2)

    3. The attempt at a solution
    This is my first post, so I apologize for any weird looking equations, etc. I know that this is not a difficult problem, but I just cannot figure out exactly how to set it up. I don't know what function to differentiate for x and y... Any guidance would be appreciated. Thank you!
     
  2. jcsd
  3. Dec 3, 2015 #2

    jedishrfu

    Staff: Mentor

    Start by determining the first derivatives of x and y with respect to ##\rho## and ##\phi## and then repeat it for the second derivatives of x and y.

    and please show your work. We can't help you without you showing your work.

    Also try learning latex when entering your symbols for consistency with other posts here at PF.

    We quote our expressions with double # front and back: #.#.\rho.#.# (remove the dots to see the rho as a greek letter)

    Here's the PF reference:

    https://www.physicsforums.com/threads/physics-forums-faq-and-howto.617567/#post-3977517

    and here's a more extensive LaTex cheat sheet:

    http://users.dickinson.edu/~richesod/latex/latexcheatsheet.pdf
     
    Last edited: Dec 3, 2015
  4. Dec 3, 2015 #3

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    2/∂x2+∂2/∂y2 is not a quantity.

    It is the Laplacian expressed in cartesian coordinates. (otherwise known as the ∇2 operator)

    http://hyperphysics.phy-astr.gsu.edu/hbase/lapl.html
     
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