# Propagation velocity

1. Nov 7, 2008

### maths08

heys,

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.

cheers
John

2. Nov 7, 2008

### physics girl phd

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 .

3. Nov 7, 2008

### maths08

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
John

4. Nov 7, 2008

### pioupioup

hey,

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 $$v=\sqrt{\frac{F}{\mu}}\quad \text{where}\quad \mu = \text{lineic mass of the string and}\quad F = \text{Restoring force applied to the string}$$

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

You can also try to find the propagating speed using matlab, you know that $$v=\frac{d}{t}$$, you can find the speed by this way.

5. Nov 7, 2008

### maths08

cheers for the replies.

It is the speed at which the tumour is propagating along the x-axis. so, what formula should I use?

6. Nov 10, 2008