Two trains, each moving with a velocity of $30\ ms^{- 1}$, cross each other. One of the trains gives a whistle whose frequency is 600Hz. If the speed of sound is $330\ ms^{- 1}$ the apparent frequency for passengers sitting in the other train before crossing would be

Question

Dr. Abubacker · Accepted Answer

(d) Given, the speed of sound $v = 330\ ms^{- 1}$
Velocity of both trains =$30\ ms^{- 1}$
$\left( \because v_{o} = v_{s} = 20ms^{- 1} \right)$
And frequency =600 Hz
When both trains are moving towards each other then, apparent frequency
$n^{'} = n\left\lbrack \frac{v + v_{o}}{v - v_{s}} \right\rbrack$
$= 600\left\lbrack \frac{330 + 30}{330 - 30} \right\rbrack$
$= 600\left\lbrack \frac{360}{300} \right\rbrack$
$n'$=720 Hz

Q. Two trains, each moving with a velocity of $30\ ms^{- 1}$, cross each other. One of the trains gives a whistle whose frequency is 600Hz. If the speed of sound is $330\ ms^{- 1}$ the apparent frequency for passengers sitting in the other train before crossing would be

Explanation

Reviewed by Dr. Abubacker

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