A train moving at a speed of 220, ms^{-1} tow | vedclass

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(C) The frequency of the echo detected by the driver of the train is calculated using the Doppler effect formula for a moving source and a moving obse

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$5000$

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(C) The frequency of the echo detected by the driver of the train is calculated using the Doppler effect formula for a moving source and a moving observer.Here,the train acts as both the source and the observer.Let $v = 330\, ms^{-1}$ be the speed of sound and $u = 220\, ms^{-1}$ be the speed of the train.When the sound travels from the train to the stationary object,the object receives a frequency $f_1 = f \left( \frac{v}{v-u} ight)$.This object then reflects the sound,acting as a stationary source,and the train (moving observer) receives the echo with frequency $f' = f_1 \left( \frac{v+u}{v} ight)$.Substituting $f_1$ into the equation for $f'$,we get:$f' = f \left( \frac{v}{v-u} ight) \left( \frac{v+u}{v} ight) = f \left( \frac{v+u}{v-u} ight)$.Substituting the given values:$f' = 1000 \left( \frac{330+220}{330-220} ight) = 1000 \left( \frac{550}{110} ight) = 1000 	imes 5 = 5000\, Hz$.

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