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Homework Help: Propagation velocity

  1. Nov 7, 2008 #1

    sorry I didn't know where to post this hopefully I will get some responses.

    well, I had a set of differential equations which I solved using MATLAB and got plots as travelling waves(t=1 to 10). basically, I need to find the velocity at which the wave is propagating and I have no idea where to start.

    any hints will be much appreciated.

  2. jcsd
  3. Nov 7, 2008 #2
    If you have individual plots of this wave as functions of position at different snapshots in time, can't you trace out how far a spot in the wave (say a peak) moves in these time intervals?

    P.S. welcome to the forums :smile:.
  4. Nov 7, 2008 #3
    Heys all,

    Thanks for the reply.. I have no knowledge of physics, however I looked at some notes for waves propagation and it gives it as c=w/k.

    In my plots, I have the spatial axis and the wave is propagating from left to right. How do I find the propagation velocity? I will post the plot if it helps.

    Any hint is really appreciated!

    Many thanks
  5. Nov 7, 2008 #4

    you can try to find this velocity mathemathically, what kind of wave is it? electromagnetic wave, wave propagating on a string,...?

    if this is a wave on a string, the speed is given by [tex]v=\sqrt{\frac{F}{\mu}}\quad \text{where}\quad \mu = \text{lineic mass of the string and}\quad F = \text{Restoring force applied to the string}[/tex]

    if the wave is an electromagnetic wave, [tex]v=\lambda f[/tex], and if the wave is a sound wave, [tex]v=\sqrt{\frac{B}{\rho_0}}, \text{where}\quad B=p_0 \gamma = p_0 . 1.4 \quad\text{(for an idealised gas), where} \quad p_0 \quad \text{is the presure of air}\quad \text{and where}\quad \rho_0\quad \text{is the volumic mass of the air}[/tex]

    You can also try to find the propagating speed using matlab, you know that [tex]v=\frac{d}{t}[/tex], you can find the speed by this way.
  6. Nov 7, 2008 #5
    cheers for the replies.

    It is the speed at which the tumour is propagating along the x-axis. so, what formula should I use?
  7. Nov 10, 2008 #6
    please someone out there help!

    I have a computer simulation (using MATLAB) of travelling waves and I need to find the speed of propagation.

    does anyone know the code in MATLAB to find how long does it take for the next wave to appear so that I can use c=x/t??

    plz help me

    many thanks
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