Can Eigenfrequencies Explain Oscillatory Behavior in this Dynamical System?

Click For Summary

Homework Help Overview

The discussion revolves around a dynamical system described by a set of coupled ordinary differential equations. The original poster is exploring the conditions under which oscillatory behavior can occur based on the eigenfrequencies derived from the system's parameters.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to establish a connection between eigenfrequencies and the oscillatory behavior of the system by formulating the equations into a matrix and calculating the determinant. Some participants suggest using specific forms for the solutions to derive the eigenfrequencies, while others question whether the solutions should account for damping.

Discussion Status

The discussion is actively exploring various interpretations of how to approach the problem. Participants are engaging with the mathematical formulation and the implications of damping in the context of eigenfrequencies, indicating a productive exchange of ideas without reaching a consensus.

Contextual Notes

Participants are working under the assumption that the material parameters A, B, and C are positive and non-zero, which may influence the behavior of the system. There is also a focus on the nature of the solutions, particularly regarding damped oscillations.

xago
Messages
60
Reaction score
0
1.
Homework Statement

Someone studying a dynamical system in another field of science tells you that when they
attempt to model the experiment they’ve been examining they obtain the following set of
coupled ordinary differential equations.

\dot{x}= -Ax + By
\dot{y}= -Cx

In what follows you should assume that the material parameters A, B, C are all positive and
non zero. They also tell you that for certain material parameters (that is, for certain A, B, C)
they can sometimes obtain oscillatory behaviour, albeit damped, but sometimes they do not.
Note that x and y are restricted to be real.

(a) Show that this is indeed possible by solving for the normal modes of this system. That is,
find the eigenfrequencies for this system.

The Attempt at a Solution



So basically my idea of eigenfrequencies are the frequencies at which the system oscillates and all motion of the system is the superposition of these two frequencies/motions. The first thing I'm doing is putting the constants into a matrix:

| -A B | |x| = |0|
| C 0 | |y|= |0|

Then i solve for determinant and get the eigenfrequencies. Basically I just wanted to know if I'm on the right track and this will help me prove that this is solving for the normal modes.
 
Physics news on Phys.org
Normal modes imply:

x(t) = D e^{i\omega t}

So you need to plug in similar functions for x and y. Then you solve for the eigenfrequences.
 
Shouldn't the function you plug in be of the form of a solution for a damped oscillation?
 
If \omega is imaginary then it will be damped.
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
Replies
4
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
Replies
3
Views
3K
  • · Replies 11 ·
Replies
11
Views
2K
Replies
2
Views
2K
  • · Replies 3 ·
Replies
3
Views
1K
Replies
3
Views
1K
Replies
4
Views
2K