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 Help!