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

Homework Help: A Lagrangian Dynamics Problem

  1. May 31, 2010 #1
    1. The problem statement, all variables and given/known data

    Hi all, I need to derive differantial equations of system with lagrange multiplier method, a disk is rolling and a bar is fixed onto the point of a disk

    [PLAIN]http://img130.imageshack.us/img130/1669/adsziss.jpg [Broken]
    By deniz120 at 2010-05-31


    2. Relevant equations



    3. The attempt at a solution
    please check my solution below, I derived T and V for Lagrange, all I need is help for constaints, lagrange multiplier equation. Thanks in advance:)

    [PLAIN]http://img263.imageshack.us/img263/3659/tarama0001r.jpg [Broken]
    By deniz120 at 2010-05-31]
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. May 31, 2010 #2

    vela

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

  4. May 31, 2010 #3
    unfortunately nothing, I guess there is nonholonomic constraint
    thanks
     
  5. May 31, 2010 #4

    vela

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    It's not a nonholonomic constraint.

    You have only two coordinates, β and θ. How are they related?
     
  6. May 31, 2010 #5
    I guess you are right but that is the exact question that I m looking for the answer, how are they related:)
     
  7. May 31, 2010 #6

    vela

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    Really? It's basic geometry. Consider the height of point B.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook