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A train is moving on a straight track wi...

A train is moving on a straight track with speed `20ms^(-1)`. It is blowing its whistle at the frequency of `1000 Hz`. The percentage change in the frequency heard by a person standing near the track as the train passes him is (speed of sound `= 320 ms^(-1)`) close to :

A

0.18

B

0.24

C

0.06

D

0.12

Text Solution

Verified by Experts

The correct Answer is:
D
`f_1=f[v/(v-v_s)]=f times320/300Hz`
`f_2=f[v/(v-v_s)]= ftimes320/340Hz`
`(f_2/(f_1)-1)times100=(300/340-1)times12%`
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