- #1
anhhuyalex
- 5
- 0
To calculate the detected frequency from the source frequency, we use this formula:
[itex]{ f }_{ D }=\frac { v\pm { v }_{ D } }{ v\pm { v }_{ s } } { f }_{ s }[/itex]
where [itex]{v}_{s}, {v}_{D}[/itex] are velocities of the source and the detector respectively with reference to the medium. My question is why do we consider motion relative to the medium? Wouldn't a detector moving at 3 m/s receiving sound from a source moving at 8 m/s in the same direction detect the same frequency as a stationary detector receiving sound from a source moving at 5 m/s? However, from the above equation, that is not true. Thanks for taking your time to answer.
[itex]{ f }_{ D }=\frac { v\pm { v }_{ D } }{ v\pm { v }_{ s } } { f }_{ s }[/itex]
where [itex]{v}_{s}, {v}_{D}[/itex] are velocities of the source and the detector respectively with reference to the medium. My question is why do we consider motion relative to the medium? Wouldn't a detector moving at 3 m/s receiving sound from a source moving at 8 m/s in the same direction detect the same frequency as a stationary detector receiving sound from a source moving at 5 m/s? However, from the above equation, that is not true. Thanks for taking your time to answer.