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A person feels 2.5% difference of freque...

A person feels 2.5% difference of frequency of a motor-car horn. If the motor-car is moving towards the person and the velocity of sound is 320 m/s, then the velocity of motor car will be (approximately)

A

8

B

800

C

7

D

6

Text Solution

Verified by Experts

The correct Answer is:
A
`Deltaf=f_(app)-f_(o)=f_(o)((v)/(v-_(s)))-f_(o)`
`(Deltaf)/(f_(o))=(v)/(v-v_(s))-1=(v_(s))/(v-v_(s))=(2.5)/(100)`
`rArr (v_(s))/(v-v_(s))=(1)/(40)rArrv_(s)=(v)/(41)=8m//s`
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