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Homework Help: Pendulum(damping coefficient)

  1. Sep 24, 2008 #1
    I am giving M=1kg, L=1.0m, T(period) = 2.02sec. I need to find C

    The pendulum is in water.

    The eq of motion is double-dot-theta+(c/m)single-dot-theta+(g/l)theta = 0

    I was doing some research and found this half life formula...T(1/2) = LN(2)/ Lamda. I am not sure where to go from here...

    I know Wn = sqrt(g/L)...
  2. jcsd
  3. Sep 24, 2008 #2


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    Hi math111! :smile:

    (have a theta: θ and a lamda: λ and use ' instead of dot :smile:)

    hmm … I'm don't think that T(1/2) is the same T that you were given. :confused:

    It is not a good idea to trawl the web looking for an equation that might fit. :frown:

    Hint: do you know any method of solving θ'' + (c/m)θ' + (g/l)θ = 0 ? :smile:
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