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Homework Help: SHM question

  1. Dec 9, 2006 #1
    1. The problem statement, all variables and given/known data
    OK I haven't been given a definite question with values, but how would you find the natural frequency of a system of two pendulums coupled by a spring?

    2. Relevant equations
    a= -gx/l
    T=2pi sqrt(l/g)

    3. The attempt at a solution
    Well the thing is, I know I need to consider each pendulum/spring separately and get two equations of motion, but I'm not sure how. All i know about pendulums are those two equations above. When I've had similar problems with springs I've been able to find the resultant force as a function of x and go from there. But in this case I just came up with the resultant -mgx/l - lamda(x-0.5l) = ma

  2. jcsd
  3. Dec 9, 2006 #2
    Some thoughts:
    Have you drawn out a picture of the system? Are the pedulums fixed at the same point at the top or are their top points separated by the natural length of the spring?

    Then: Can you use free body diagrams to find out the forces on the bobs of the pendulums? What if you displace one bob in the system by a small angle?
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