(1) Suppose an oncoming ambulance moving at 115 km/h emits a steady 810-Hz sound from its siren.
Part (a) What frequency, in Hz, is received by a person watching the oncoming ambulance? The speed of sound on this day is 345 m/s.
Part (b) What frequency, in Hz, does she observe after the ambulance has passed?
(2). In this problem take the speed of sound to be 349 m/s.
How fast, in meters per second, does an observer need to approach a stationary sound source in order to observe a 4.5 % increase in the emitted frequency?
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