# How is longitudinal wave spread

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1. Feb 17, 2016

1. The problem statement, all variables and given/known data
http://s11.postimg.org/pm7hxibo3/vala.png
Here is how the transverse wave is spread in T/4, T/2, 3T/4, T (T- period)
I need the same graph for the longitudinal wave.

2. Relevant equations
X=c*T (c-velocity of moving of the wave)

3. The attempt at a solution
In this picture it is shown a longitudinal wave. How can I show how it is spread in T/4, T/2, 3T/4, T? Where will the rarefaction and compression be in different times?

2. Feb 17, 2016

### BvU

Same graph, only arrows go left-right instead of up-down. See e.g. here

By the way, you call that 'propagating', not 'spreading'.

And yes, rarefaction (valley) will be T/2 after compression (peak), just like in a transverse wave + maximum and - minimum are T/2 apart in time.

Similarly, rarefaction (valley) will be $\lambda$/2 behind compression (peak), just like in a transverse wave + maximum and - minimum are $\lambda$/2 apart in distance.

3. Feb 17, 2016

http://s30.postimg.org/igw0ava9t/vala1.png
I caught some moments from a video. Is each picture T/4, T/2, 3T/4, T? If no could you please draw it correctly? Thanks

4. Feb 17, 2016

Last edited: Feb 17, 2016
5. Feb 17, 2016

### BvU

Would you please first render the litteral problem statement ?
And: what relevant equations do you have to represent graphically ? $X = ct$ is a straight line....

6. Feb 17, 2016

I haven't got any equation to represent. I just wrote it because it is necessary to writ an equation related, but it has nothing to do with the solution. I just want the longitudinal wave spreading graphic

7. Feb 17, 2016

### haruspex

I find that drawing very hard to interpret.
I suggest starting with the diagram you first linked, showing a spring with various sections of it under compression and tension. You could try adding arrows of different lengths and directions to that, illustrating which parts are moving forward fastest etc.
To help construct that, you could make a second copy of the spring picture underneath and shifted a bit to the right, thereby showing where everything will be a a short time after the first picture.