- #1
FireBones
- 103
- 0
A sound wave can be interpreted in any of four ways. Two of those involve the correspondence between (1)displacement and position and (2)pressure and position.
[By "position" here I refer to the distance from the source. Positive refers to going away from the source.]
These waves are 90 degrees out of phase. My questions are:
1) Is it always the case that the pressure wave "leads" [it attains a maximum a quarter period before the displacement attains a maximum.]
2) If it is not always the case, what determines whether the pressure leads or lags?
An important correlation to pressure leading displacement is that velocity is always negatively proportional to pressure. In other words, a particle is always moving fastest forward in rarefaction and fastest backward in compression. Is there a slick intuitive reason for this?
I'm wondering if any of this depends on the maximum displacement speed of a particle versus the speed of the wave itself.
A reference from page 477 of Physics for scientists and engineers: http://books.google.com/books?id=up...re wave time equilibrium displacement&f=false
[By "position" here I refer to the distance from the source. Positive refers to going away from the source.]
These waves are 90 degrees out of phase. My questions are:
1) Is it always the case that the pressure wave "leads" [it attains a maximum a quarter period before the displacement attains a maximum.]
2) If it is not always the case, what determines whether the pressure leads or lags?
An important correlation to pressure leading displacement is that velocity is always negatively proportional to pressure. In other words, a particle is always moving fastest forward in rarefaction and fastest backward in compression. Is there a slick intuitive reason for this?
I'm wondering if any of this depends on the maximum displacement speed of a particle versus the speed of the wave itself.
A reference from page 477 of Physics for scientists and engineers: http://books.google.com/books?id=up...re wave time equilibrium displacement&f=false