Unformatted text preview: as measured relative to the stationary medium, i.e. the air. In a measurement frame in which the air is stationary, the horn and the sleeper are both traveling at the same velocity so the sleeper hears no Doppler shift and the perceived frequency is 1000 Hz. What frequency does a seagull blown along with the wind hear? a) 179 Hz; b) 990 Hz; c) 1010 Hz; d) 1029 Hz; e) 971 Hz. What do you know? The bird is stationary in the moving air and thinks the fog horn is traveling away from him. This produces a lowering of the frequency he hears because the wavelength in the air is longer than it would be if the air and the horn were at rest relative to one another. Thus Hz Hz v v v v f f S O 971 10 343 343 1000 '...
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- Spring '04
- Hertz, Hz, Sonar, kHz fog horn