How Far Must a Sound Source Move to Create Silence Due to the Doppler Effect?

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SUMMARY

The discussion centers on calculating the distance a sound source must move to create silence for an observer due to the Doppler Effect. Two sound sources emitting a frequency of 800 Hz in air (with a speed of sound at 340 m/s) are analyzed. The key solution involves determining the distance required for destructive interference, where the sound waves are out of phase by π radians. The initial approach of calculating wavelength to drop the frequency below 20 Hz was incorrect, as the observer's hearing capability was not specified.

PREREQUISITES
  • Understanding of the Doppler Effect and its implications on sound frequency.
  • Familiarity with wave interference, specifically destructive interference.
  • Knowledge of basic wave properties, including frequency and wavelength calculations.
  • Proficiency in using the formula f' = f/(1 + vsource/vsnd) for sound wave analysis.
NEXT STEPS
  • Research the principles of wave interference and how to calculate conditions for destructive interference.
  • Study the Doppler Effect in various mediums, including air and water.
  • Explore advanced sound wave properties, including phase shifts and their impact on sound perception.
  • Learn about the mathematical modeling of sound waves and their applications in acoustics.
USEFUL FOR

Students studying physics, acoustics researchers, and anyone interested in sound wave behavior and interference patterns.

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Homework Statement


Two adjacent sources each emit frequency 800 hz in air (340 m/s). how far would source 1 have to be moved so an observer in front of the sources would hear no sound? .321 .213 .123 or .312.


Homework Equations


f' = f/(1+ vsource/vsnd)


The Attempt at a Solution



i tried to calculate wavelength so that the frequency is below 20 hz (human limit) and figure it out from there but I am stuck? please help, thank you
 
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The observer wasn't specified to be human...so we cannot assume that we would have to take it so that the frequency is below 20Hz. Rather, what you should do is find the distance of separation between the 2 sources so that the waves they emit destructively interfere (the waves are out of phase by pi).
 

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