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A policeman on duty detects a drop of 10...

A policeman on duty detects a drop of `10%` in the pitch of the horn of a moving car as it crosses him. If the velocity of sound is `330 m//s`, the speed of the car will be

A

`20 m//sec`

B

`17.3 m//sec`

C

`25 m//sec`

D

`27 m//sec`

Text Solution

AI Generated Solution

To solve the problem, we will use the concept of the Doppler effect, which describes how the frequency of a wave changes for an observer moving relative to the source of the wave. ### Step-by-Step Solution: 1. **Understanding the Problem**: - We know that the pitch (frequency) of the horn drops by 10% as the car moves past the policeman. This means that if the original frequency is \( F_1 \), the observed frequency \( F_2 \) is \( 90\% \) of \( F_1 \) (i.e., \( F_2 = 0.9 F_1 \)). - The speed of sound \( C \) is given as \( 330 \, \text{m/s} \). ...
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