Engineering Board Exam Reviewer · Physics · hard
An ambulance siren emits 500 Hz while approaching a stationary observer at 30 m/s. What frequency does the observer hear? (speed of sound = 343 m/s)
- 547.9 Hz
- 459.8 Hz
- 543.7 Hz
- 500.0 Hz
Answer
A. 547.9 Hz
Solution
Source approaching: f' = f · v/(v - vs) = 500(343)/(313) = 547.9 Hz.
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