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Point on Circle Derivation

  1. Mar 8, 2012 #1
    Hi All,

    I am working on the problem of bead on wire and got stuck on some basic derivation detail.
    I took the same approach as Andrew Witkin used in his slide (page 13):

    Here is the screenshot of the slide page 13:
    http://desmond.imageshack.us/Himg831/scaled.php?server=831&filename=pocs.png&res=medium [Broken]

    As we can see, C is the function of x and r is constant. x is a function of t as well.

    I got stuck on deriving the third line of the equation (the derivative of N with respect to t). My derivation result seems different from what the author proposed.
    Here is my step by step derivation:
    http://img269.imageshack.us/img269/8623/derivative.png [Broken]

    Could somebody point out my mistake? Any help will be greatly appreciated.

    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Mar 10, 2012 #2
    Nevermind. I have solved this problem.
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