A siren placed at a railway platform is emitting sound of frequency 5 kHz. A passenger sitting in a moving train A, records a frequency of 5.5 kHz while the train approaches the siren. During his return journey in a different train B, he records a frequency of 6.0 kHz while approaching the same siren. The ratio of the velocity of train B to that of train A is

$\frac{242}{252}$

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$\frac{5}{6}$

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$\frac{11}{6}$

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Solution

The correct option is B
2

In both the cases observer is moving towards, the source. Hence by using $n^{'}$ = $n (\frac{v + v_{0}}{v})$

When passenger is sitting in train A, then

$5.5$ = $5 (\frac{v + v_{A}}{v})$ ......(i)

When passenger is sitting in train B, then

$6$ = $5 (\frac{v + v_{B}}{v})$

On solving equation (i) and (ii), we get $\frac{v_{B}}{v_{A}}$ = $2$

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Similar questions

Q. A siren placed at a railway platform is emitting sound of frequency 5 kHz. A passenger sitting in a moving train A records a frequency of 5.5 kHz while the train approaches the siren. During his return journey in a different train B he records a frequency of 6.0 kHz while approaching the
same siren. The ratio of velocity of train B to that of train A is

Q. A siren placed at a railway platform is emitting sound of frequency

5 k H z

. A passenger sitting in a moving train A records a frequency of

5.5 k H z

while the train approaches the siren. During his return journey in a different train

B

he records a frequency of

6.0 k H z

while approaches the same siren. The ratio of the velocity of train

B

to that train

A

A siren placed at a railway platform is emitting sound of frequency 5 kHz. A passenger sitting in a moving train A, records a frequency of 5.5 kHz while the train approaches the siren. During his return journey in a different train B, he records a frequency of 6.0 kHz while approaching the same siren. The ratio of the velocity of train B to that of train A is

Q. A train is moving with a constant speed

15 m / s

along a circular track. The length of the train makes an angle

90^{0}

at the centre. A siren in its engine is emitting a sound of frequency

1.5 k H z

. The apparent frequency of sound as heard by a passenger at the rear end of the train is

x / 2 k H z

, then find the value of

x

Q. An observer standing on a railway crossing receives frequencies of 2.2 kHz and 1.8 kHz when the train approaches and recedes from the observer. Find the velocity of the train in m/s.
[The speed of the sound in air is 300 m/s]

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The correct option is B 2 In both the cases observer is moving towards, the source. Hence by using n′ = n(v+v0v) When passenger is sitting in train A, then 5.5 = 5(v+vAv) ......(i) When passenger is sitting in train B, then 6 = 5(v+vBv) On solving equation (i) and (ii), we get vBvA = 2