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Solving for Stiffness using a plot

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  • Subject: [mg99896] Solving for Stiffness using a plot
  • From: twoseat <caseyktimmons at>
  • Date: Tue, 19 May 2009 06:41:30 -0400 (EDT)


 I am trying to use mathematica to solve for the stiffness of a spring system but I cannot figure out how to plot my equations correctly.

 I have: 
k; (*temp. I am solving for this*)

a = NDSolve[{k[x1[t] - x2[t]]*(x1[t] - x2[t]) - m1*x1''[t] == 0, 
   m1*x1''[t] - m2*x2''[t] == 0,  x1[0] == 0,  x2[0] == 0,  
   x1'[0] == v0, x2'[0] == 0}, {x1[t], x2[t]}, {t, -10, 20}]
dis = Plot[Evaluate[{x1[t] - x2[t]} /. a], {t, -10, 20}]

This gives me multiple errors and wont plot. 

 I am going to try to plot k[x1[t]-x2[t]]*(x1[t]-x2[t]) vs (x1[t]-x2[t]) to solve for k but I can't determine how to set up my equations to plot. 

Any help or recommendations would be appreciated!

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