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A police car with a siren of frequency 8...

A police car with a siren of frequency 8 kHz is moving with uniform velocity 36 km/h towards a tall building which reflects the sound waves. The speed of sound in air is 320 m/s. The frequency of the siren heard by the car driver is

A

`8.50 kHz`

B

`8.25 kHz`

C

`7.75 kHz`

D

`7.50 kHz`

Text Solution

Verified by Experts

The correct Answer is:
A

`f_("insident") = f_("reflected") = (320)/(320 - 10) xx 8 kHz`
`f_("observal") = (320 + 10)/(320) f_("reflected") = 8 xx (330)/(310) = 8.51 kHz approx 8.5 kHz`
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RESONANCE ENGLISH-SOUND WAVES-Exercise- 3 PART - I
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