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I About the formula of pendulum -- What if there is damping?

  1. Mar 14, 2016 #1
    http://physics.stackexchange.com/questions/243457/about-the-formula-of-pendulum-simple [Broken]

    a(t) = a0 * sin ( sqrt(g/l) * t * Pi/2 ) - [ k/(mll) * cos ( sqrt(g/l) * t * Pi/2 ) * t ) ]

    a(t) : the angle in instant t .
    t : time
    g : gravity .
    Pi = 3.14
    k = Fixed (Friction )
    l : longer of pendulum

    but this formula is wrong , because the curve of this formula Remains constant , like this :
    K9i9f.png

    I want to correct this equation to become true Means keeps decreasing curve, even non-existent ( = 0 ) . lwTAG.png
    Specifically I want to change in the second part , in [ k/(m*l*l) * cos ( sqrt(g/l) * t * Pi/2 ) * t ) ]

    can you help me ? Are there any other equation?
     

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    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Mar 15, 2016 #2

    BvU

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