1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Second order ODE application question

  1. Apr 16, 2011 #1
    We are doing mass spring problems that stem from second order ODE's. I think my lack of linear algebra is hurting me once again in this section so any help would be greatly appreciated.
    We are using a stiffness matrix of K = [ -(k1+k2), k2 (row 2) k2, -(k2+k3)]
    Our first problem has the following values: m1=m2=1; k1=0, k2=2, k3=0
    Setting up the stiffness matrix I got the following:
    -2 2
    2 -2
    So this is my first stopping point: I thought you were supposed to then take the inverse of that but can you do that with a matrix that has a determinant of zero?
     
  2. jcsd
  3. Apr 16, 2011 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    hi cue928! :smile:

    not really my subject, so i'm going to risk asking what could be a really dumb question :redface:

    if there's only two degrees of freedom, how come there's three parameters? :confused:

    (and your general formula doesn't have rows summing to 0 …

    maybe these are just the top triangle of a 3x3 matrix?)​
     
  4. Apr 16, 2011 #3
    I don't know how to answer that. Since there is a zero value for two of them, maybe that has something to do with it? I honestly don't know.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Similar Discussions: Second order ODE application question
Loading...