A source, approaching with speed u towards the open end of a stationary pipe of length L , is emitting a sound of frequency f s . The farther end of the pipe is closed. The speed of sound in air is v and f 0 is the fundamental frequency of the pipe. For which of the following combination(s) of u and f s , will the sound reaching the pipe lead to a resonance?

u = 0 . 5 v and f s = 1 . 5 f 0

u = 0 . 8 v and f s = 0 . 5 f 0

In an experiment, to measure the speed of sound by a resonating air column, a tuning fork of frequency 500 Hz is used. The length of the air column is varied by changing the level of water in the resonance tube. Two successive resonances are heard at air columns of length 50 .7 cm and 83 .9 cm . Which of the following statements is (are) true?

The wavelength of the sound wave is 66 .4 cm .

The resonance at 50 .7 cm corresponds to the fundamental harmonic.

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Two vehicles, each moving with speed $u$ on the same horizontal straight road, are approaching each other. The wind blows along the road with velocity $w$ . One of these vehicles blows a whistle of frequency $f_{1}$ . An observer in the other vehicle hears the frequency of the whistle to be $f_{2}$ . The speed of sound in still air is $v$ . The correct statement (s) is (are):

33.33% studentsanswered this correctly

Important Questions on Mechanical Wave

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JEE Advanced

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Mechanical Wave>JEE Advanced Paper 1 - 2020>Q 6

A stationary tuning fork is in resonance with an air column in a pipe. If the tuning fork is moved with a speed of

2 m s^{- 1}

in front of the open end of the pipe and parallel to it, the length of the pipe should be changed for the resonance to occur with the moving tuning fork. If the speed of sound in air is

320 m s^{- 1},

the smallest value of the percentage change required in the length of the pipe is ________.

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JEE Advanced

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Mechanical Wave>JEE Advanced Paper 1 - 2019>Q 7

A train

S 1,

moving with a uniform velocity of

108 k m / h,

approaches another train

S 2

standing on a platform. An observer

O

moves with a uniform velocity of

36 k m / h

towards

S 2,

as shown in figure. Both the trains are blowing whistles of same frequency

120 H z .

When

O

600 m

away from

S 2

and distance between

S 1

and

S 2

800 m,

the number of beats heard by

O

is____.

[Speed of the sound

= 330 m s^{- 1}]

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JEE Advanced

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Mechanical Wave>JEE Advanced Paper 1 - 2018>Q 8

Two vectors

\vec{A}

and

\vec{B}

are defined as

\vec{A} = a \hat{i}

and

\vec{B} = a (\cos ω t \hat{i} + \sin ω t \hat{j})

, where a is a constant and

ω = \frac{π}{6} rad s^{- 1} .

|\vec{A} + \vec{B}| = \sqrt{3} |\vec{A} - \vec{B}|

at time

t = τ

for the first time, the value of

τ

in seconds, is_______

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JEE Advanced

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Mechanical Wave>JEE Advanced Paper 1 - 2018>Q 9

Two men are walking along a horizontal straight line in the same direction. The man in front walks at a speed

1 .0 m s^{- 1}

and the man behind walks at a speed

2 .0 m s^{- 1}

. A third man is standing at a height

12 m

above the same horizontal line such that all three men are in a vertical plane. The two walking men are blowing identical whistles which emit a sound of frequency

1430 Hz

. The speed of sound in air is

330 m s^{- 1}

. At the instant, when the moving men are

10 m

apart, the stationary man is equidistant from them. The frequency of beats in

Hz

, heard by the stationary man at this instant, is __________.

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JEE Advanced

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Mechanical Wave>JEE Advanced Paper 1 - 2017>Q 10

A block

M

hangs vertically at the bottom end of a uniform rope of constant mass per unit length. The top end of the rope is attached to a fixed rigid support at O. A transverse wave pulse (Pulse 1) of wavelength

λ_{0}

is produced at point O on the rope. The pulse takes time

T_{O A}

to reach point A. If the wave pulse of wavelength

λ_{0}

is produced at point A (Pulse 2) without disturbing the position of M it takes time

T_{O A}

to reach point O. Which of the following options is/are correct?
Question Image

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JEE Advanced

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Mechanical Wave>JEE Advanced Paper 1 - 2016>Q 12

Two loudspeakers

M

and

N

are located

20 m

apart and emit sound at frequencies

118 Hz

and

121 Hz

, respectively. A car is initially at a point

P

1800 m

away from the midpoint

Q

of the line

M N

and moves towards

Q

constantly at

60 km h^{- 1}

along the perpendicular bisector of

M N

. It crosses

Q

and eventually reaches a point

R

1800 m

away from

Q

. Let

ν (t)

represent the beat frequency measured by a person sitting in the car at time

t

. Let

ν_{p}, ν_{Q} and ν_{R}

be the beat frequencies measured at locations

P, Q

and

R

, respectively. The speed of sound in air is

330 m s^{- 1} .

Which of the following statement(s) is (are) true regarding the sound heard by the person?

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JEE Advanced

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Mechanical Wave>JEE Advanced Paper 1 - 2014>Q 13

A student is performing an experiment using a resonance column and a tuning fork of frequency

244 s^{- 1}

. He is told that the air in the tube has been replaced by another gas (assume that the column remains filled with the gas). If the minimum height at which resonance occurs is

(0.350 \pm 0.005) m

, the gas in the tube is (Useful information:

\sqrt{167 R T} = 640 J^{\frac{1}{2}} m o l^{- \frac{1}{2}}; \sqrt{140 R T} = 590 J^{\frac{1}{2}} m o l^{- \frac{1}{2}}

. The molar masses

M

in grams are given in the options. Take the values of

\sqrt{\frac{10}{M}}

for each gas as given there.)

HARD

JEE Advanced

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Mechanical Wave>JEE Advanced Paper 1 - 2014>Q 14

One end of a taut string of length 3m along the x axis is fixed at x = 0. The speed of the waves in the string is

100 m s^{- 1}

. The other end of the string is vibrating in the y direction so that stationary waves are set up in the string. The possible waveform(s) of these stationary waves is (are)

Important Questions on Mechanical Wave

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