How does one begin to derive the resonant frequencies of a multiple mass mass-spring system? (3-mass system) OK, so deriving this isn't a homework problem. I'd just like to know how. It's been a couple of years since I've taken a physics course. I was asked what the resonant frequencies of each mode of a 3-mass mass-spring system was. I found the formulas on the internet, but am not sure how these are derived. Does anyone know how to derive these? ...If anyone could get me started on one, that would be great. Relevant equations can be found in this PDF document for each mode of oscillation, page 13 & 14! academic.reed.edu/physics/courses/phys100/Lab%20Manuals/Vibrational%20Modes/normalmodes.pdf (There are accompanying images in the PDF that I can't format the same way on a forum) Does anyone have any suggestions on where to begin? Thanks!