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3 years ago

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The police car with its 300-Hz siren is moving away from the warehouse at a speed of 16.0 m/s . . . What frequency does the driv

er of the police car hear reflected from the warehouse?. . Use 344m/s for the speed of sound in air.

2 answers:

bazaltina [42]3 years ago

8 0

Frequency heard by listener: fl = ?
frequency of source: fs = 300 Hz
velocity of listener: vl = 16 m/s
velocity of source: vs = 0
<span>velocity of sound in air: c = 344 m/s

</span><span>fl = fs [(c – vl)/c] = 300[(344-16)/344]
</span> =286.04 Hz

Morgarella [4.7K]3 years ago

4 0

<h3><u>Answer;</u></h3>

= 286.05 Hz

<h3><u>Explanation;</u></h3>

We can use or employ the Doppler equation:

<em><u>fl = fs[(c±vl)/(c-/+vs) </u></em>

where,

frequency heard by listener: fl = ?
frequency of source: fs = 300 Hz
velocity of listener: vl = 16 m/s
velocity of source: vs = 0
velocity of sound in air: c = 344 m/s

The source will be the origin of the reflected signal (i.e.the

warehouse). So that, velocity of source: vs = 0

<em>The listener is the policeman moving away from the source </em>

<em>with velocity: vl = 16 m/s</em>

<em>Therefore, the Doppler equation. becomes: </em>

<em>fl = fs [(c – vl)/c] </em>

<em>= 300[(344-16)/344] </em>

<u><em>= 286.04 Hz </em></u>

where, fl is the frequency of the reflected sound heard by

the police officer.

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