First slide

Doppler's effect

Question

A motor car blowing a horn of frequency 124 vib/sec moves with a velocity 72 km/hr towards a tall wall. The frequency of the reflected sound heard by the driver will be (velocity of sound in air is 330 m/s)

Difficult

A

109 vib/sec
B

132 vib/sec
C

140 vib/sec
D

248 vib/sec

Solution

Similar to previous question
The frequency of reflected sound heard by the driver
$n^{'} = n (\frac{v - (- v_{0})}{v - v_{s}}) = n (\frac{v + v_{0}}{v - v_{s}})$
$= 124 [\frac{330 + (72 \times 5 / 18)}{330 - (72 \times 5 / 18)}] = 140 vibration / \sec$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App