   Complex pendulum
  I''m trying to simulate the following in two dimensions.A fixed point on a ceiling connected to A rod R1 of fixed length L1 connected to A weight W1 of mass M1 connected toA rod R2 of fixed length L2 connected to A weight W2 of mass M2 connected to... for N weightsAn object can then hit any of the weights with a force F.As far as I can see, each Weight Wi has the following forces acting on it:1) Gravity2) Force F from outside stimulus3) Central Motion acceleration towards position of Wi-1 due to motion.4) Force propogating from previous weight Wi-1 if it exists5) Force propogating from next weight Wi+1 if it exists1,2 and 3 are relatively easy to calculate but does anyone know how I calculate 4 and 5?Many thanks for any ideas 
  I don''t know your maths knowledge or experience but it looks to me like Lagrangian mechanics would be a good tool. Basically you have everything in terms of the minimum number of measurements you need to determine the system (conjugate coordinates). Here the obvious choice would be the angle of each rod with the vertical. If you have no idea what I''m talking about it''s university level mechanics I''m afraid! ;  I have  a relatively good knowledge of mechanics but never quite got to Lagrangian.  I''ll go and look it up and see what I can do.Thanks 