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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/hr 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 = `(320)/(320 - 10 ) xx 8 xx 10^(3) xx (320 + 10)/(320) = 8.5 ` kHz
So , correct choice is a.
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