# Wavelength of sound and windspeed

1. ### nil1996

299
Both source and observer are at rest. If the wind blows from source to observer will the wind affect the wavelength of sound??

2. ### Simon Bridge

15,274
Excellent question: how are attempting to answer it so far?

3. ### nil1996

299
i am thinking like if the wind speed is u and sound speed is v then the observer will notice that the sound is at speed v+u. Wave length is the distance between two compressions. The wind is moving the whole medium with the speed u. So i think there will be no change in wavelength as the successive compressions will be both moving at an additional speed u. Is that right??

4. ### Simon Bridge

15,274
I think the issue here is what we are comparing the wavelength to.
The wavelength without the wind perhaps?
And with respect to whome?

So the source makes compressions and rarifactions with period T.
The wind whips them away ... so instead of moving at speed c, they move at speed c+v.

5. ### nil1996

299
oh,got it so the wavelength should be (v+c)/f
f = frequency

6. ### nil1996

299
The wind takes the first compression made by the source further by c*T before the second compression is released.Right??

7. ### Simon Bridge

15,274
That's what I figured - but it's your work.

What if the air was still but both source and detector were moving?