Mass spring system where springs have mass

[sleventh]

hello all,
Recently I have been attempting to model a spring system (see below) where the springs themselves will hold mass. I should know how to do this but i accept defeat, how do you model the potential energy or a force system on two masses connected to three springs? I have read about effective mass but i fail to fully understand. Thank you all for the celerity.
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[M1]
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[M2]
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In this design the spring system is vertical and grounded on both ends. Many thanks!

 

[Eynstone]

Just apply Newton's laws. If l1,l2,l3 are the lengths of the springs at a time t ,l1+l2+l3 =constant due to the grounding. Hence, you get two equations in two unknowns.

 

[sleventh]

yes I've been doing that and also derived the kinetic energy for the springs (1/6 mv^2 because of the springs mass per length) but am having difficulty compiling the kinetic energies and potentials.