System of Second Order, Nonhomogeneous Differential Equations

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Discussion Overview

The discussion revolves around solving a system of second order, nonhomogeneous differential equations, specifically in the context of engineering applications involving masses, damping coefficients, and spring constants. Participants explore methods for deriving and solving these equations both analytically and numerically.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant expresses difficulty in solving a system of second order, nonhomogeneous equations, having experience only with single second order equations and systems of first order equations.
  • Another participant speculates that the variable g represents gravity, suggesting that the problem involves masses suspended from a structure.
  • A participant clarifies that the variables m, c, and k represent masses, damping coefficients, and spring constants, respectively, and notes that these are positive constants specified by the user in a MATLAB program.
  • Further, the participant outlines the need to write differential equations for a system of three masses connected by springs and dashpots, and to solve these equations by hand before implementing a numerical method in MATLAB.
  • Another participant suggests defining a new vector to facilitate the rewriting of the equations, indicating a method for approaching the solution of the ordinary differential equations (ODEs).

Areas of Agreement / Disagreement

Participants generally agree on the nature of the problem involving masses, damping, and spring constants, but the discussion remains unresolved regarding the specific methods for solving the system of equations.

Contextual Notes

Participants have not yet specified all assumptions or provided complete mathematical formulations, and the discussion does not resolve the steps needed to derive or solve the equations fully.

mccormas
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Hello. I am an engineering student and am having trouble trying to figure out how to solve this system of second order, nonhomogeneous equations. I know how to solve a single second order, nonhomo. equation and how to solve a system of first orders, but not this one. Any help would be greatly appreciated. I have attached a scanned image of the equation because I couldn't format it right on here and it won't let me just post a URL because I'm new on here.


That is a g tucked in there on the right side of the equation. Thanks again.
 

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keeping in mind that you are an engineering student, I would speculate and assume that g is gravity, the masses are hanged from somewhere. and in general, you are required the solve the x(t) for each mass.
 
Exactly. I probably should have specified that earlier. The m's are masses, c's are damping coefficients and k's are spring constants. All are positive constants that will be specified by the user in the MATLAB program that I have to write. First, though, I need to figure out how to solve the problem by hand. Then I have to choose a numerical method we've learned and implement it in an M-file on MATLAB.

The problem has 3 masses hanging by springs and dashpots. We have to write the differential equations for the system and then solve it using a self-written m-file.
 
Then, define a new vector,

[tex] \hat x = \left( {\begin{array}{*{20}c}<br /> x \\<br /> {\dot x} \\<br /> \end{array}} \right)<br /> [/tex]

From the fact
[tex] \frac{d}{dt}\hat x = \left( {\begin{array}{*{20}c}<br /> \dot{x} \\<br /> {\ddot x} \\<br /> \end{array}} \right)<br /> [/tex]

Rewrite the equations again. and then solve a ODE set.
 

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