Question

A police car travels towards a stationary
observer at a speed of 15 m/s. The siren
on the car emits a sound of frequency 250
Hz. Calculate the recorded frequency.
The speed of sound is 340 m/s.​

Answer 1

Question :-

A police car travels towards a stationary

observer at a speed of 15 m/s. The siren

on the car emits a sound of frequency 250

Hz. Calculate the recorded frequency.

The speed of sound is 340 m/s.

Answer :-

• The frequency heard by the audience as the car approaches stand is 261.54Hz.

Step by step explanation :-

Given :

$\bullet\sf\:{v_s = 15m/s} \\ \\\bullet\sf\:{n_0 = 250Hz} \\ \\ \bullet\sf\:{v= 340m/s}$

Need to find :

• Frequency (n)

Formula :

$\bigstar\: \sf{n = n_0 \bigg( \frac{v}{v - v_s} \bigg)}$

⏩ As the source approaches listener, apparent frequency is given by,

$\sf:\longmapsto{n =250 \bigg( \frac{340}{340 - 15} \bigg) } \\ \\ \sf:\longmapsto{n = 250 \bigg( \frac{340}{325} \bigg) } \: \: \: \: \: \: \: \: \: \\ \\ \sf:\longmapsto{n = 250 \bigg( \frac{68}{65} \bigg)} \: \: \: \: \: \: \: \: \: \: \\ \\ \sf:\longmapsto{n = \frac{17000}{65} } \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ \bf:\longmapsto \red{n = 261.54} \: \: \: \: \: \: \: \: \: \: \: \: \:$

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Learn more from brainly :

The sound emitted from the siren of an

ambulance has frequency of 1500 HZ

The speed of sound is 340 m/s. Calculate

the difference in frequencies heard by

a stationary observer it the ambulance

initially. travels towards and then away

from the observer at a speed of 30 m/s.

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