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PHXI15:WAVES

354736 The engine of a train moving with speed $10 m s^{- 1}$ towards a platform sounds a whistle at frequency $400 H z$ . The frequency heard by a passenger inside the train is (Neglect air speed. Speed of sound in air is $330 m s^{- 1}$ )

1

400 H z

2

388 H z

3

412 H z

4

200 H z

Explanation:

$400 H z$ , as passenger is inside the train relative velocity between the source and the passenger B zero. So, passenger will hear the sound of same frequency as generated by train.

JEE - 2023

PHXI15:WAVES

354737 Two trains move towards each other with the same speed. Speed of sound is $340 m s^{- 1}$ . If the frequency of the tone of the whistle of one when heard on the other is $9 / 8$ times the original value. Then the speed of each train is :
supporting img

1

40 m s^{- 1}

2

2 m s^{- 1}

3

100 m s^{- 1}

4

20 m s^{- 1}

Explanation:

$\frac{f_{2}}{f_{1}} = \frac{9}{8}$
$f_{2} = (\frac{v + v_{0}}{v - v_{s}}) f_{1} (∵ v_{s} = v_{0})$
$\Rightarrow \frac{9}{8} = \frac{v + v_{0}}{v - v_{0}}$
$\Rightarrow v_{0} = 20 m / s$

PHXI15:WAVES

354738 Two trains ' $A$ ' and ' $B$ ' are moving away from one another with a speed of $720 k m p h$ . The apparent frequency of the whistle blown by as heard by the passenger of the train ' $B$ ' is (velocity of sound in air is $350 m s^{- 1}$ ) (given whistle frequency $1100 H z$ )

1

300 H z

2

400 H z

3

500 H z

4

600 H z

Explanation:

$n_{B} = (\frac{V - V_{B}}{V + V_{A}}) n_{A}$
$f^{'} = 1100 (\frac{350 - 200}{350 + 200})$
$= 1100 \times \frac{150}{550}$
$= 300 H z$

PHXI15:WAVES

354739 A source of sound is in the middle of the line joining the position of two persons $A$ and $B$ , air is blowing from $B$ to $A$ . Then

1

A

will hear first

2

B

will hear first

3 Both will hear at a time

4 Sound is heard by neither

A

nor

B

Explanation:

Because of wind flow from $B$ to $A$ the velocity of sound wave w.r.to ground is more from the wave that reach $A$ .

PHXI15:WAVES

354740 A police car moving at $22 m / s$ chases a motorcyclist. The police man sounds his horn at $176 H z$ , while both of them move towards a stationary siren of frequency $165 H z$ . Calculate the speed of the motorcycle. If it is given that the motorcyclist does not observe any beats: (Given velocity of sound $330 m / s$ )
supporting img

1

33 m / s

2

22 m / s

3 Zero

4

11 m / s

Explanation:

As no beats are observed $f_{1} = f_{2}$
$176 (\frac{330 - v_{0}}{330 - 22}) = 165 (\frac{330 + v_{0}}{330})$
$v_{0} = 22 m / \sec$

PHXI15:WAVES

354736 The engine of a train moving with speed $10 m s^{- 1}$ towards a platform sounds a whistle at frequency $400 H z$ . The frequency heard by a passenger inside the train is (Neglect air speed. Speed of sound in air is $330 m s^{- 1}$ )

1

400 H z

2

388 H z

3

412 H z

4

200 H z

Explanation:

$400 H z$ , as passenger is inside the train relative velocity between the source and the passenger B zero. So, passenger will hear the sound of same frequency as generated by train.

JEE - 2023

PHXI15:WAVES

354737 Two trains move towards each other with the same speed. Speed of sound is $340 m s^{- 1}$ . If the frequency of the tone of the whistle of one when heard on the other is $9 / 8$ times the original value. Then the speed of each train is :
supporting img

1

40 m s^{- 1}

2

2 m s^{- 1}

3

100 m s^{- 1}

4

20 m s^{- 1}

Explanation:

$\frac{f_{2}}{f_{1}} = \frac{9}{8}$
$f_{2} = (\frac{v + v_{0}}{v - v_{s}}) f_{1} (∵ v_{s} = v_{0})$
$\Rightarrow \frac{9}{8} = \frac{v + v_{0}}{v - v_{0}}$
$\Rightarrow v_{0} = 20 m / s$

PHXI15:WAVES

354738 Two trains ' $A$ ' and ' $B$ ' are moving away from one another with a speed of $720 k m p h$ . The apparent frequency of the whistle blown by as heard by the passenger of the train ' $B$ ' is (velocity of sound in air is $350 m s^{- 1}$ ) (given whistle frequency $1100 H z$ )

1

300 H z

2

400 H z

3

500 H z

4

600 H z

Explanation:

$n_{B} = (\frac{V - V_{B}}{V + V_{A}}) n_{A}$
$f^{'} = 1100 (\frac{350 - 200}{350 + 200})$
$= 1100 \times \frac{150}{550}$
$= 300 H z$

PHXI15:WAVES

354739 A source of sound is in the middle of the line joining the position of two persons $A$ and $B$ , air is blowing from $B$ to $A$ . Then

1

A

will hear first

2

B

will hear first

3 Both will hear at a time

4 Sound is heard by neither

A

nor

B

Explanation:

Because of wind flow from $B$ to $A$ the velocity of sound wave w.r.to ground is more from the wave that reach $A$ .

PHXI15:WAVES

354740 A police car moving at $22 m / s$ chases a motorcyclist. The police man sounds his horn at $176 H z$ , while both of them move towards a stationary siren of frequency $165 H z$ . Calculate the speed of the motorcycle. If it is given that the motorcyclist does not observe any beats: (Given velocity of sound $330 m / s$ )
supporting img

1

33 m / s

2

22 m / s

3 Zero

4

11 m / s

Explanation:

As no beats are observed $f_{1} = f_{2}$
$176 (\frac{330 - v_{0}}{330 - 22}) = 165 (\frac{330 + v_{0}}{330})$
$v_{0} = 22 m / \sec$

PHXI15:WAVES

354736 The engine of a train moving with speed $10 m s^{- 1}$ towards a platform sounds a whistle at frequency $400 H z$ . The frequency heard by a passenger inside the train is (Neglect air speed. Speed of sound in air is $330 m s^{- 1}$ )

1

400 H z

2

388 H z

3

412 H z

4

200 H z

Explanation:

$400 H z$ , as passenger is inside the train relative velocity between the source and the passenger B zero. So, passenger will hear the sound of same frequency as generated by train.

JEE - 2023

PHXI15:WAVES

354737 Two trains move towards each other with the same speed. Speed of sound is $340 m s^{- 1}$ . If the frequency of the tone of the whistle of one when heard on the other is $9 / 8$ times the original value. Then the speed of each train is :
supporting img

1

40 m s^{- 1}

2

2 m s^{- 1}

3

100 m s^{- 1}

4

20 m s^{- 1}

Explanation:

$\frac{f_{2}}{f_{1}} = \frac{9}{8}$
$f_{2} = (\frac{v + v_{0}}{v - v_{s}}) f_{1} (∵ v_{s} = v_{0})$
$\Rightarrow \frac{9}{8} = \frac{v + v_{0}}{v - v_{0}}$
$\Rightarrow v_{0} = 20 m / s$

PHXI15:WAVES

354738 Two trains ' $A$ ' and ' $B$ ' are moving away from one another with a speed of $720 k m p h$ . The apparent frequency of the whistle blown by as heard by the passenger of the train ' $B$ ' is (velocity of sound in air is $350 m s^{- 1}$ ) (given whistle frequency $1100 H z$ )

1

300 H z

2

400 H z

3

500 H z

4

600 H z

Explanation:

$n_{B} = (\frac{V - V_{B}}{V + V_{A}}) n_{A}$
$f^{'} = 1100 (\frac{350 - 200}{350 + 200})$
$= 1100 \times \frac{150}{550}$
$= 300 H z$

PHXI15:WAVES

354739 A source of sound is in the middle of the line joining the position of two persons $A$ and $B$ , air is blowing from $B$ to $A$ . Then

1

A

will hear first

2

B

will hear first

3 Both will hear at a time

4 Sound is heard by neither

A

nor

B

Explanation:

Because of wind flow from $B$ to $A$ the velocity of sound wave w.r.to ground is more from the wave that reach $A$ .

PHXI15:WAVES

354740 A police car moving at $22 m / s$ chases a motorcyclist. The police man sounds his horn at $176 H z$ , while both of them move towards a stationary siren of frequency $165 H z$ . Calculate the speed of the motorcycle. If it is given that the motorcyclist does not observe any beats: (Given velocity of sound $330 m / s$ )
supporting img

1

33 m / s

2

22 m / s

3 Zero

4

11 m / s

Explanation:

As no beats are observed $f_{1} = f_{2}$
$176 (\frac{330 - v_{0}}{330 - 22}) = 165 (\frac{330 + v_{0}}{330})$
$v_{0} = 22 m / \sec$

PHXI15:WAVES

354736 The engine of a train moving with speed $10 m s^{- 1}$ towards a platform sounds a whistle at frequency $400 H z$ . The frequency heard by a passenger inside the train is (Neglect air speed. Speed of sound in air is $330 m s^{- 1}$ )

1

400 H z

2

388 H z

3

412 H z

4

200 H z

Explanation:

$400 H z$ , as passenger is inside the train relative velocity between the source and the passenger B zero. So, passenger will hear the sound of same frequency as generated by train.

JEE - 2023

PHXI15:WAVES

354737 Two trains move towards each other with the same speed. Speed of sound is $340 m s^{- 1}$ . If the frequency of the tone of the whistle of one when heard on the other is $9 / 8$ times the original value. Then the speed of each train is :
supporting img

1

40 m s^{- 1}

2

2 m s^{- 1}

3

100 m s^{- 1}

4

20 m s^{- 1}

Explanation:

$\frac{f_{2}}{f_{1}} = \frac{9}{8}$
$f_{2} = (\frac{v + v_{0}}{v - v_{s}}) f_{1} (∵ v_{s} = v_{0})$
$\Rightarrow \frac{9}{8} = \frac{v + v_{0}}{v - v_{0}}$
$\Rightarrow v_{0} = 20 m / s$

PHXI15:WAVES

354738 Two trains ' $A$ ' and ' $B$ ' are moving away from one another with a speed of $720 k m p h$ . The apparent frequency of the whistle blown by as heard by the passenger of the train ' $B$ ' is (velocity of sound in air is $350 m s^{- 1}$ ) (given whistle frequency $1100 H z$ )

1

300 H z

2

400 H z

3

500 H z

4

600 H z

Explanation:

$n_{B} = (\frac{V - V_{B}}{V + V_{A}}) n_{A}$
$f^{'} = 1100 (\frac{350 - 200}{350 + 200})$
$= 1100 \times \frac{150}{550}$
$= 300 H z$

PHXI15:WAVES

354739 A source of sound is in the middle of the line joining the position of two persons $A$ and $B$ , air is blowing from $B$ to $A$ . Then

1

A

will hear first

2

B

will hear first

3 Both will hear at a time

4 Sound is heard by neither

A

nor

B

Explanation:

Because of wind flow from $B$ to $A$ the velocity of sound wave w.r.to ground is more from the wave that reach $A$ .

PHXI15:WAVES

354740 A police car moving at $22 m / s$ chases a motorcyclist. The police man sounds his horn at $176 H z$ , while both of them move towards a stationary siren of frequency $165 H z$ . Calculate the speed of the motorcycle. If it is given that the motorcyclist does not observe any beats: (Given velocity of sound $330 m / s$ )
supporting img

1

33 m / s

2

22 m / s

3 Zero

4

11 m / s

Explanation:

As no beats are observed $f_{1} = f_{2}$
$176 (\frac{330 - v_{0}}{330 - 22}) = 165 (\frac{330 + v_{0}}{330})$
$v_{0} = 22 m / \sec$

PHXI15:WAVES

354736 The engine of a train moving with speed $10 m s^{- 1}$ towards a platform sounds a whistle at frequency $400 H z$ . The frequency heard by a passenger inside the train is (Neglect air speed. Speed of sound in air is $330 m s^{- 1}$ )

1

400 H z

2

388 H z

3

412 H z

4

200 H z

Explanation:

$400 H z$ , as passenger is inside the train relative velocity between the source and the passenger B zero. So, passenger will hear the sound of same frequency as generated by train.

JEE - 2023

PHXI15:WAVES

354737 Two trains move towards each other with the same speed. Speed of sound is $340 m s^{- 1}$ . If the frequency of the tone of the whistle of one when heard on the other is $9 / 8$ times the original value. Then the speed of each train is :
supporting img

1

40 m s^{- 1}

2

2 m s^{- 1}

3

100 m s^{- 1}

4

20 m s^{- 1}

Explanation:

$\frac{f_{2}}{f_{1}} = \frac{9}{8}$
$f_{2} = (\frac{v + v_{0}}{v - v_{s}}) f_{1} (∵ v_{s} = v_{0})$
$\Rightarrow \frac{9}{8} = \frac{v + v_{0}}{v - v_{0}}$
$\Rightarrow v_{0} = 20 m / s$

PHXI15:WAVES

354738 Two trains ' $A$ ' and ' $B$ ' are moving away from one another with a speed of $720 k m p h$ . The apparent frequency of the whistle blown by as heard by the passenger of the train ' $B$ ' is (velocity of sound in air is $350 m s^{- 1}$ ) (given whistle frequency $1100 H z$ )

1

300 H z

2

400 H z

3

500 H z

4

600 H z

Explanation:

$n_{B} = (\frac{V - V_{B}}{V + V_{A}}) n_{A}$
$f^{'} = 1100 (\frac{350 - 200}{350 + 200})$
$= 1100 \times \frac{150}{550}$
$= 300 H z$

PHXI15:WAVES

354739 A source of sound is in the middle of the line joining the position of two persons $A$ and $B$ , air is blowing from $B$ to $A$ . Then

1

A

will hear first

2

B

will hear first

3 Both will hear at a time

4 Sound is heard by neither

A

nor

B

Explanation:

Because of wind flow from $B$ to $A$ the velocity of sound wave w.r.to ground is more from the wave that reach $A$ .

PHXI15:WAVES

354740 A police car moving at $22 m / s$ chases a motorcyclist. The police man sounds his horn at $176 H z$ , while both of them move towards a stationary siren of frequency $165 H z$ . Calculate the speed of the motorcycle. If it is given that the motorcyclist does not observe any beats: (Given velocity of sound $330 m / s$ )
supporting img

1

33 m / s

2

22 m / s

3 Zero

4

11 m / s

Explanation:

As no beats are observed $f_{1} = f_{2}$
$176 (\frac{330 - v_{0}}{330 - 22}) = 165 (\frac{330 + v_{0}}{330})$
$v_{0} = 22 m / \sec$