Solving for non moving points of a 1-D wave

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Homework Help Overview

The original poster attempts to find the stationary points on a 1-D wave described by a function u(x,t) that represents the displacement of a string over time. The goal is to identify the values of x in the interval (0, 1) where the wave does not move, meaning u(x,t) remains zero for all t > 0.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the interpretation of the wave function and its implications for finding stationary points. The original poster simplifies the problem by evaluating at t=0 and differentiating to find where the velocity is zero. Some participants suggest examining the time derivative of the function to identify conditions for non-moving points.

Discussion Status

There are multiple lines of reasoning being explored, including the use of trigonometric identities to simplify the expressions. Some participants provide guidance on using polynomial forms and factoring techniques, while others express uncertainty about the application of these methods. The discussion remains open with various approaches being considered.

Contextual Notes

Participants note the complexity of the trigonometric terms involved and the challenges of using software tools like Maple for simplification. There is an emphasis on finding systematic solutions rather than relying on graphical approximations.

  • #31
yes heh, considering I don't know how to get maple to do anything correctly, what are some alternatives to find the roots? Thanks
 
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  • #32
Well, the expression In post #18 is fully factored...that means that the roots of the ugly factor are going to be difficult to find...BUT! you don't need to find them because they will all depend on \beta, whioch means they will only be roots for certain values of t, and as I said in post #28, that means that those roots are not stationary points...do you not understand this?
 
  • #33
yes but...so am I suppose to say that even though they seem to be stationary, that's not the case since they will be dependent on beta?
 
  • #34
Why do you say "they seem to be stationary"?
 
  • #35
That's because we were to graph 10 plots at various t, I decidedly went t=1..10 and from the graphs the roots looked stationary

Also I had the impression that the problem would've been simpler in terms of all the trig stuff...
 
  • #36
Oh...try graphing it for t=0.2 and t=0.4...do they still look stationary?
 
  • #37
It definitely does not. So I did a bad job in choosing the appropriate time interval then? My graphs definitely made me think I'd be getting answers for nonmoving x values...
 
  • #38
regardless... Thank you very much for being so patient. It makes sense how you approached this problem now. once again, Thanks! :P
 

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