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Suppose an oncoming ambulance moving at 110 km/h emits a steady 825-hz sound from its siren.

What frequency, in Hz, is received by a person watching the oncoming ambulance?

User ScottA
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Final answer:

Using the Doppler Effect formula, the frequency received by a person as an oncoming ambulance approaches, which is moving at 110 km/h and emitting a steady 825 Hz sound, is approximately 905 Hz.

Step-by-step explanation:

The student's question involves calculating the observed frequency of sound from an ambulance approaching a stationary listener, which is an application of the Doppler Effect. The Doppler Effect is observed when a source of sound is moving relative to an observer, causing a shift in the frequency heard by the observer.

To calculate the frequency received by the person, we will use the formula:

f' = f * ((v + vo) / (v - vs))

Where:






First, convert vs from km/h to m/s: 110 km/h * (1000 m/km) / (3600 s/h) = 30.56 m/s

Now, plug the values into the formula:

f' = 825 Hz * ((345 m/s + 0 m/s) / (345 m/s - 30.56 m/s))

f' = 825 Hz * (345 m/s / 314.44 m/s)

f' = 825 Hz * 1.097

f' ≈ 905 Hz

Therefore, the frequency received by the person as the ambulance approaches is approximately 905 Hz.

User Spycho
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