A bus is moving with a velocity of $5ms^{- 1}\ $towards a huge wall. The driver sounds a horn of frequency 165 Hz. If the speed of sound in air is $335\ ms^{- 1}$, the number of beats heard per second by a passenger inside the buss will be

Question

Dr. Abubacker · Accepted Answer

(c) Apparent frequency
$v^{'} = v\left( \frac{v - v_{L}}{v - v_{s}} ight)$
$= 165\left( \frac{355 + 5}{355 - 5} ight)$
$\left( \because v_{L} = - 5ms^{- 1},\ v_{s} = 5ms^{- 1} ight)$
$= 165 	imes \frac{340}{330} = 170\ Hz\ $
Therefore, the number of beats heard
=170-165=5

Q. A bus is moving with a velocity of $5ms^{- 1}\ $towards a huge wall. The driver sounds a horn of frequency 165 Hz. If the speed of sound in air is $335\ ms^{- 1}$, the number of beats heard per second by a passenger inside the buss will be

Explanation

Reviewed by Dr. Abubacker

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