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Standard XII

Physics

String Open at One End

A car is movi...

Question

A car is moving at speed of 54 $k m / h r$ and produces a sound of frequency 630 $H z$ . A person running with a speed of $2 m / s$ is approaching the car. What frequency would the person hear? (speed of sound = $330 m / s$ )

635

H z

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646

H z

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653

H z

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664

H z

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Solution

The correct option is D 664 $H z$
$n_{a p p} = n_{0} {\frac{v + v_{p}}{v - v_{s}}}$
$= 630 (\frac{330 + 2}{330 - 15})$
$= \frac{630 \times 332}{315} = 664 H z$

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A car is moving at speed of 54 km/hr and produces a sound of frequency 630 Hz . A person running with a speed of 2 m/s is approaching the car. What frequency would the person hear? (speed of sound = 330 m/s)

The correct option is D 664 Hznapp=n0{v+vpv−vs} =630(330+2330−15) =630×332315=664 Hz

A car is moving at speed of 54 $k m / h r$ and produces a sound of frequency 630 $H z$ . A person running with a speed of $2 m / s$ is approaching the car. What frequency would the person hear? (speed of sound = $330 m / s$ )

The correct option is D 664 $H z$
$n_{a p p} = n_{0} {\frac{v + v_{p}}{v - v_{s}}}$
$= 630 (\frac{330 + 2}{330 - 15})$
$= \frac{630 \times 332}{315} = 664 H z$