doppler shift (physics)?

Question

why is there a doppler effect when the source of sound is staionary and the listener is in motion? in which direction should the listener move to hear a higher frequency? a lower frequency?

Answer 1

The Doppler effect is applicable moving or stationary observers.
It is irrelevant if observer is mowing towards the source or it is the source that is moving towards the observe or even both. Their relative velocities will add up (in Newtonian frame of course)

The speed of propagation of a wave in a particular medium is a constant, So something must give...

V=Lf
V - speed of the propagating wave
L - wavelength of the wave
f - frequency of the wave.

so if a source is approaching the observer at say Va velocity

then we would expect
V+ Va= Lf would we not however the speed of sound is the speed it approaches

V=Ld fd
fd - the frequency we hear

The detected frequency fd increases for objects moving toward the observer, the source's velocity must be subtracted when motion is moving toward the observer.

So the frequency the observer will hear is
fd= [V/(V+/- Va)] f

Answer 2

If the speed of the source will develop it variations the frequency of the sound accomplishing you greater dramatically, and that makes the sound distinctive. If the speed of the easily waves will develop then variations in the speed of the source impact it much less. Ex. A firetruck traveling 10000kph in direction of you will sound so severe pitch that a 5kph wave speed develop will extremely be discernible. If a similar truck become traveling 10kph then that 5kph difference may be significant. Your wording become a splash uncertain i wish I helped.

Answer 3

Moving toward the sound, its frequency increases and decreases when you pass it and move away.
(Moving toward the sound causes compression of the sound waves and de-compression when moving away).