Applications of coupled systems of $;2times 2;$ linear differential equations












0














I am providing maths help to some students studying just before University level in mathematics.



I am writing some practice questions for them on solving coupled first order linear equations and I was wondering if there are any 'real-life' applications of this.



I am having difficulty finding examples because the systems they need to solve are restricted to two dependent variables and one independent variable and need to be linear. (Most of the easy go-to options, e.g. SIR models, are not linear).



I have already used:




  • predator-prey problems

  • two-tanks mixing problems


Are there any others?



[For information, the equations they are required to solve should be of the form



$frac{dx}{dt} = ax + by + f(t), hspace{3mm} frac{dy}{dt} = cx + dy + g(t)$.]










share|cite|improve this question





























    0














    I am providing maths help to some students studying just before University level in mathematics.



    I am writing some practice questions for them on solving coupled first order linear equations and I was wondering if there are any 'real-life' applications of this.



    I am having difficulty finding examples because the systems they need to solve are restricted to two dependent variables and one independent variable and need to be linear. (Most of the easy go-to options, e.g. SIR models, are not linear).



    I have already used:




    • predator-prey problems

    • two-tanks mixing problems


    Are there any others?



    [For information, the equations they are required to solve should be of the form



    $frac{dx}{dt} = ax + by + f(t), hspace{3mm} frac{dy}{dt} = cx + dy + g(t)$.]










    share|cite|improve this question



























      0












      0








      0


      1





      I am providing maths help to some students studying just before University level in mathematics.



      I am writing some practice questions for them on solving coupled first order linear equations and I was wondering if there are any 'real-life' applications of this.



      I am having difficulty finding examples because the systems they need to solve are restricted to two dependent variables and one independent variable and need to be linear. (Most of the easy go-to options, e.g. SIR models, are not linear).



      I have already used:




      • predator-prey problems

      • two-tanks mixing problems


      Are there any others?



      [For information, the equations they are required to solve should be of the form



      $frac{dx}{dt} = ax + by + f(t), hspace{3mm} frac{dy}{dt} = cx + dy + g(t)$.]










      share|cite|improve this question















      I am providing maths help to some students studying just before University level in mathematics.



      I am writing some practice questions for them on solving coupled first order linear equations and I was wondering if there are any 'real-life' applications of this.



      I am having difficulty finding examples because the systems they need to solve are restricted to two dependent variables and one independent variable and need to be linear. (Most of the easy go-to options, e.g. SIR models, are not linear).



      I have already used:




      • predator-prey problems

      • two-tanks mixing problems


      Are there any others?



      [For information, the equations they are required to solve should be of the form



      $frac{dx}{dt} = ax + by + f(t), hspace{3mm} frac{dy}{dt} = cx + dy + g(t)$.]







      differential-equations soft-question applications






      share|cite|improve this question















      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Dec 26 '18 at 19:03









      user376343

      2,8382822




      2,8382822










      asked Dec 26 '18 at 18:32









      PhysicsMathsLove

      1,189314




      1,189314






















          1 Answer
          1






          active

          oldest

          votes


















          -1














          Coupled harmonic oscillators are a good example. The outer rectangles are walls, the inner ones are masses and the lines are springs. The heavy lines are strong springs. If you write it in terms of the positions of each mass, the coupling spring shifts the frequencies up and down a bit. You can do the linear algebra to show that the modes are symmetric and antisymmetric and that the correct basis is in those terms.



          enter image description here






          share|cite|improve this answer





















          • How would you set up first order differential equations for these particles, rather than second order?
            – David Quinn
            Dec 26 '18 at 18:51










          • You are right, I was thinking of linear but not first order. You can make it first order in four variables by defining the velocities as new variables.
            – Ross Millikan
            Dec 27 '18 at 5:22













          Your Answer





          StackExchange.ifUsing("editor", function () {
          return StackExchange.using("mathjaxEditing", function () {
          StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
          StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
          });
          });
          }, "mathjax-editing");

          StackExchange.ready(function() {
          var channelOptions = {
          tags: "".split(" "),
          id: "69"
          };
          initTagRenderer("".split(" "), "".split(" "), channelOptions);

          StackExchange.using("externalEditor", function() {
          // Have to fire editor after snippets, if snippets enabled
          if (StackExchange.settings.snippets.snippetsEnabled) {
          StackExchange.using("snippets", function() {
          createEditor();
          });
          }
          else {
          createEditor();
          }
          });

          function createEditor() {
          StackExchange.prepareEditor({
          heartbeatType: 'answer',
          autoActivateHeartbeat: false,
          convertImagesToLinks: true,
          noModals: true,
          showLowRepImageUploadWarning: true,
          reputationToPostImages: 10,
          bindNavPrevention: true,
          postfix: "",
          imageUploader: {
          brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
          contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
          allowUrls: true
          },
          noCode: true, onDemand: true,
          discardSelector: ".discard-answer"
          ,immediatelyShowMarkdownHelp:true
          });


          }
          });














          draft saved

          draft discarded


















          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3053193%2fapplications-of-coupled-systems-of-2-times-2-linear-differential-equations%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown

























          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          -1














          Coupled harmonic oscillators are a good example. The outer rectangles are walls, the inner ones are masses and the lines are springs. The heavy lines are strong springs. If you write it in terms of the positions of each mass, the coupling spring shifts the frequencies up and down a bit. You can do the linear algebra to show that the modes are symmetric and antisymmetric and that the correct basis is in those terms.



          enter image description here






          share|cite|improve this answer





















          • How would you set up first order differential equations for these particles, rather than second order?
            – David Quinn
            Dec 26 '18 at 18:51










          • You are right, I was thinking of linear but not first order. You can make it first order in four variables by defining the velocities as new variables.
            – Ross Millikan
            Dec 27 '18 at 5:22


















          -1














          Coupled harmonic oscillators are a good example. The outer rectangles are walls, the inner ones are masses and the lines are springs. The heavy lines are strong springs. If you write it in terms of the positions of each mass, the coupling spring shifts the frequencies up and down a bit. You can do the linear algebra to show that the modes are symmetric and antisymmetric and that the correct basis is in those terms.



          enter image description here






          share|cite|improve this answer





















          • How would you set up first order differential equations for these particles, rather than second order?
            – David Quinn
            Dec 26 '18 at 18:51










          • You are right, I was thinking of linear but not first order. You can make it first order in four variables by defining the velocities as new variables.
            – Ross Millikan
            Dec 27 '18 at 5:22
















          -1












          -1








          -1






          Coupled harmonic oscillators are a good example. The outer rectangles are walls, the inner ones are masses and the lines are springs. The heavy lines are strong springs. If you write it in terms of the positions of each mass, the coupling spring shifts the frequencies up and down a bit. You can do the linear algebra to show that the modes are symmetric and antisymmetric and that the correct basis is in those terms.



          enter image description here






          share|cite|improve this answer












          Coupled harmonic oscillators are a good example. The outer rectangles are walls, the inner ones are masses and the lines are springs. The heavy lines are strong springs. If you write it in terms of the positions of each mass, the coupling spring shifts the frequencies up and down a bit. You can do the linear algebra to show that the modes are symmetric and antisymmetric and that the correct basis is in those terms.



          enter image description here







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 26 '18 at 18:41









          Ross Millikan

          291k23196371




          291k23196371












          • How would you set up first order differential equations for these particles, rather than second order?
            – David Quinn
            Dec 26 '18 at 18:51










          • You are right, I was thinking of linear but not first order. You can make it first order in four variables by defining the velocities as new variables.
            – Ross Millikan
            Dec 27 '18 at 5:22




















          • How would you set up first order differential equations for these particles, rather than second order?
            – David Quinn
            Dec 26 '18 at 18:51










          • You are right, I was thinking of linear but not first order. You can make it first order in four variables by defining the velocities as new variables.
            – Ross Millikan
            Dec 27 '18 at 5:22


















          How would you set up first order differential equations for these particles, rather than second order?
          – David Quinn
          Dec 26 '18 at 18:51




          How would you set up first order differential equations for these particles, rather than second order?
          – David Quinn
          Dec 26 '18 at 18:51












          You are right, I was thinking of linear but not first order. You can make it first order in four variables by defining the velocities as new variables.
          – Ross Millikan
          Dec 27 '18 at 5:22






          You are right, I was thinking of linear but not first order. You can make it first order in four variables by defining the velocities as new variables.
          – Ross Millikan
          Dec 27 '18 at 5:22




















          draft saved

          draft discarded




















































          Thanks for contributing an answer to Mathematics Stack Exchange!


          • Please be sure to answer the question. Provide details and share your research!

          But avoid



          • Asking for help, clarification, or responding to other answers.

          • Making statements based on opinion; back them up with references or personal experience.


          Use MathJax to format equations. MathJax reference.


          To learn more, see our tips on writing great answers.





          Some of your past answers have not been well-received, and you're in danger of being blocked from answering.


          Please pay close attention to the following guidance:


          • Please be sure to answer the question. Provide details and share your research!

          But avoid



          • Asking for help, clarification, or responding to other answers.

          • Making statements based on opinion; back them up with references or personal experience.


          To learn more, see our tips on writing great answers.




          draft saved


          draft discarded














          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3053193%2fapplications-of-coupled-systems-of-2-times-2-linear-differential-equations%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown





















































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown

































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown







          Popular posts from this blog

          Human spaceflight

          Can not write log (Is /dev/pts mounted?) - openpty in Ubuntu-on-Windows?

          張江高科駅