Doppler Effect
Sound from a moving source sounds different than from a stationary source.
If the source is moving toward you, the sound will be higher in pitch.
If the source is moving away from you, the sound will be lower in pitch.
This is known as the Doppler effect.
If the source is moving toward you, the sound will be higher in pitch.
If the source is moving away from you, the sound will be lower in pitch.
The details are given by the equation
where f' is the frequency that is heard with a moving source (or observer), f is the frequency heard with source and observer at rest, v is the speed of sound, vobs is the speed of the observer, and vsource is the speed of the source.
[ Be careful with the sign conventions!
For
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