Sound Waves Questions and Answers

33 34 35 1 2 A person B accidentally slips from a large building and screams with a sound of constant frequency n as he falls as shown in the figure The apparent frequency of the sound of the scream as heard by the person A at the top of the building is dependent on time as v is speed of sound n n B 36 Question Type Single Correct Type 3 n n V v gt V n n gt 37 38 39 40 41 2v 2x at EEEE 000 4

23 A string of length L is stretched by L 20 and speed of transverse wave along it is v The speed of wave when it is stretched by L 10 will be assume that Hooke s law is applicable a 2v c 2v b d 4v

A bus is moving towards a huge wall with a velocity of 5 m s The driver sounds a horn of frequency 200 Hz The frequency of the beats heard by a passenger of the bus will be In Hz nearly velocity of sound in air 338 m s

24 An organ pipe closed at one end has fundamental frequency of 1500 Hz The maximum number of overtones generated by this pipe which a normal person can hear is AIIMS 2004 1 14 2 13 3 6 4 9

n n n v gt w n 2v4gi n n n n n 2v 2v gt2 A person B accidentally slips from a large building and screams with a sound of constant frequency n as he falls as shown in the figure The apparent frequency of the sound of the scream as heard by the person A at the top of the building is dependent on time as v is speed of sound B 000 000 000 14 26 000 14 26

Question No 45 Single Correct A n n A gt A person B accidentally slips from a large building and screams with a sound of constant frequency n as he falls as shown in the figure The apparent frequency of the sound of the scream as heard by the person A at the top of the building is dependent on time as v is speed of sound LANGUAGE ENGLISH 000 000 Marks 4 00 1 00 CHI

0 A stationary source emits sound waves of frequency 500 Hz Two observers moving along a line passing through the source detect sound to be of frequencies 480 Hz and 530 Hz Their respective speeds are in ms Take speed of sound 300 m s JEE Main 2019 10 April Shift 1 a 12 16 b 12 18 c 16 14 d 8 18 Exp b Given

In a long cylindrical tube an air column is constructed by fitting a movable piston A tuning fork of frequency 416Hz sends longitudinal sound waves Consider the speed of sound in the air as 333m s It is observed that the air column in the tube vibrates in its fundamental frequency How far from the open end should the piston be in this situation A 10cm B 20cm C 30cm D 40cm

A certain radar operates at a wavelength of 50 cm If the beat frequency between the transmitted signal and the signal reflected from aircraft Af 1kH then what will be the velocity in km h of the aircraft Correct Answer 900

a Find the length of an organ pipe closed at one end that produces a fundamental frequency of 256 Hz when air temperature is 18 0 C b What is its fundamental frequency at 25 0 C We will use the following relation when finding the speed of sound in different temperatures 7331 273

A vibrating tuning fork of frequency n is placed near the open end of a long cylindrical tube The tube has a side opening and is also fitted with a movable reflecting piston As the piston is moved through 8 75 cm the intensity of sound changes from a maximum to minimum If the speed of sound is 350 metre per second then n is 1 500 Hz 3 2000 Hz Ear 2 1000 Hz 4 4000 Hz

A submarine A travelling at 18 km h is being chased along the line of its velocity by another submarine B travelling at 27 km h B sends a sonar signal of 500 Hz to detect A and receives a reflected sound of frequency v The value of v is close to Speed of sound in water 1500 ms 2019 Main 12 April I a 504 Hz b 507 Hz c 499 Hz d 502 Hz

6 5 10 W O 3 3x10 W O 9 9x10 W O 3 1 10 W 4 9 10 2 W 2 0 10 W Question 8 You are walking between two stationary speakers A and B that both play a constant note with frequency 440 Hz You are walking towards speaker B at a constant speed of v 2 6 m s as shown below Speaker A 6 7 Hz 1 What beat frequency do you hear Assuming the speed of sound is 343 m s O 1 7 Hz Speaker B 3 pts

12 The fundamental frequency of an open organ pipe is 300 Hz then which of the following is wrong 1 First overtone is 600 Hz 2 Fourth overtone is 1500 Hz 3 Second overtone is 900 Hz 4 First overtone is 450 Hz A source of sound S is moving along line QP by making an angle 60 with SO where O is the

14 A and B are two hills at a distance 480 m apart A person standing between the hills claps his hands and hears two echoes at the end of 1 second and 2 seconds The velocity of sound in air in m s is 1 320 m s 2 160 m s 3 330 m s 4 340 m s

A stationary observer receives sound from two identical tuning forks one of which approaches and the other one recedes with the same speed much less than the speed of sound The observer hears 2 beats sec The oscillation frequency of each tuning fork is vo 1400 Hz and the velocity of sound in air is 350 m s The speed of each tuning fork is close to 2 m s 4 m s 3 1 m s

A tuning fork of frequency 480 Hz is sounded on a resonance tube The first and second resonance are observed at 16 cm and 50 cm respectively The velocity of sound in air is approximately 326 m s 300 m s 340 m s 350 m s

17 The wave function for a particle constrained to move in one dimension is shown in the graph below p 0 for x 0 and x 5 What is the probability that the particle would be found between x 2 and x 4 Y O 17 64 O 25 64 O 5 8 O 5 8 O 13 16 1 2 3 4 5 6 X

Two factories are sounding their sirens at 800 Hz A man goes from one factory to other at a speed of 2 m s The velocity of sound is 320 m s The number of beats heard by the person in one second will be A 2 C 8 B 4 D 10

The walls and ceiling of an auditorium are covered with a fibrous material to O Make the auditorium fire proof O Absorb sound and prevent echoes O Give an ethnic look to the auditorium O To prevent leakage of water from the roof

Figure shows a closed pipe closed at both ends of length 10 m MN is a membrane thin sheet capable of doing simple harmonic motion of amplitude 1 mm along left and right from shown situation On two sides of membrane are two gases G and G2 in which sound can travel at 300 m s and 100 m s respectively Mark the INCORRECT statement s A M A G 2 3 6m N G 4m B A If resonance is obtained in right side G side G might not resonate B Resonance in both gases will be possible for some specific frequencies only C For angular frequency 75 7 rad sec a particle 2 3 m right of AA would be oscillating with maximum displacement 0 5 mm D For angular frequency 75 7 rad sec a particle m right of AA would be oscillating with maximum 3

2 Increases by 37 5 3 Increases by 30 5 4 Decreases by 37 5 A tuning fork of known frequency 256 Hz makes 5 beats per second with the vibrating string of piano when tension in the wire of piano increased 2 then beat frequency decreases by 2 beats per seconds the frequency of piano string before increase in tension will be 1 251 Hz 2 256 Hz 3 261 Hz 4 253 Hz 1 In standing wave all particles between two nodes passes through mea position 1 2 3 3 3 4 17 An observ stationar wavelengt

A car is fited with a device which produces sound of frequency 50 Hz There is no wind and speed of sound in still alr is 345 ms An observer moving towards car with speed of 1 hear sound of frequency 68 Hz The speed of the car is O 20 ms towards observer O 25 m towards observer O 30 m towards observer O 30 ms away from observer View

A car is fitted with a device which produces sound of frequency 60 Hz There is no wind and speed of sound in stil air is 345 m s 1 An observer moving towards car with speec of 12 m s 1 hear sound of frequency 68 Hz The speed of th car is 20 m s 1 towards observer 25 m s1 towards observer 30 m s 1 towards observer 30 m s 1 away from observer

A source x of unknown frequency produces 8 beats with a source of 250 Hz and 12 beats with a source of 270 Hz The frequency of source x is Question Type Single Correct Type 1 258 Hz 2 242 Hz 3 262 Hz

A 43 m long rope of mass 5 kg joins two rock climbers One climber strikes the rope and the second feels the pulse effect 1 4 second later The tension in rope is nearly 110 N 135 N 70 N 2 32 N

Velocity of sound in medium is V If the density of the medium is doubled what will be the new velocity of sound 1 2V 3 4V 2 V 4 IS V

A train is moving with a constant speed along a circular track The engine of the train emits a sound of frequency f The frequency heard by the guard at rear end of the train A is less than f B is greater than f C is equal to f D may be greater than less than or equal to fdepending on the factors like speed of train length of train and radius of circular track

A tuning fork A of unknown frequency produces 5 beat s with a fork of known frequency 340 Hz When fork A is filed the beat frequency decreases to 2 beats s What is the frequency of fork A 1 345 Hz 2 338 Hz 3 335 Hz 342 Hz

The wavelengths 40 195 per second separately with a third note of fixed frequency The velocity of sound in air in m s is 1 360 m and of two sound notes in air are m Each note produces 9 beats 40 193 2 320 3 300 4 340

30 A listener moves toward statio constant speed and crosses him then correct graph between apparent frequency f with time t is 1 3 f f 14 t 2 14 f 4 f l t Dond New Delhi 110005 Ph 011 4762345

diagram below shows an instantaneous position of a string as a transverse progressive wave travels along it from left to right b a Which one of the following correctly shows the direction of the velocity of the points a b and c on the string b a 1 2 3 11 C C

The input power to a device is 10 000 W at a voltage of 1000 V The output power is 500 W while the output impedance is 20 a Find the power gain in decibels b Find the voltage gain in decibels c Explain why parts a and b agree or disagree

The frequencies of three tuning forks A B and C have a relation n ng nc When the forks A and B are sounded together the number of beats produced is n When A and C are sounded together the number of beats produced is n then the number of beats produced when B and C are sounded together is 1 n 1 3 1 1 n n 2 4 n 1 2

A man standing between two cliffs claps his hands and starts hearing a series of echoes at intervals of 2 sec Since the speed of sound in air is 340 m sec The distance between the cliffs must be 1 340 m 3 1020 m 2 680 m 4 170 m

In a resonace air column experiment first and second resonances are obtained at lengths of air columns 1 and the third resonance will be obtained at a length of 1 21 1 2 27 3 1 4 3 1

A source of sound is travelling with a velocity of 30 m s towards a stationary observer If actual frequency of source is 1000 Hz and the wind is blowing with velocity 20 m s in a direction at 60 with the direction of motion of source then the apparent frequency heard by observer is speed of sound is 340 m s

A train moves towards a stationary observer with speed 34 m s The train sounds a whistle and its frequency registered by the observer is f If the train s speed is reduced to 17 m s the frequency registered is f2 If the speed of sound of 340 m s then the ratio f f2 is

5 A tube closed at one end has a vibrating diaphragm at the other end which may be assumed to be a displacement node It is found that when the frequency of the diaphragm is 2000 Hz a stationary wave pattern is set up in which the distance between adjacent nodes is 8 cm When the frequency is gradually reduced the stationary wave pattern disappears but another stationary wave pattern reappears at a frequency of 1600 Hz Calculate a the speed of sound in air b the distance between adjacent nodes at a frequency of 1600 Hz c the distance between the diaphragm and the closed end

A light pointer fixed to one prong of a tuning fork touches a vertical plate The fork is set vibrating and plate is allowed to fall freely 8 complete oscillations are counted when the plate falls through 10 cm What is the frequency of the tuning fork

A square hinged structure ABCD is formed with four massless rods which lies on the smooth horizontal table The hinge D of structure is fixed with table and hinge A hinge B and hinge C are free to move on the table A point mass m is attached at hinge B and an ideal spring of stiffness k is connected between hinge A and hinge C as shown in the figure System is in equilibrium The mass m is slightly displaced along line BD and released to perform SHM The time period of SHM is nm Find A oooooooooo

c 60 9 Two sound sources emitting sound each of wavelength are fixed at a given distance apart A listener moves with a velocity u along the line joining the two sources The number of beats heard by him per second is 2000 a b c 1 22 d 2u

c 60 Two sound sources emitting sound each of wavelength are fixed at a given distance apart A listener moves with a velocity u along the line joining the two sources The number of beats heard by him per second is 2000 b a c 2 1 22 d a

The length of the wire shown in figure between the pulleys is 1 5 m and its mass is 12 0 g The frequency of vibration with which the wire vibrates in three loops forming antinode at the mid point of the wire is g 9 8 m s Question Type Single Correct Type 1 2 210 Hz 140 Hz 19kg 3 70 Hz 9kg

21 A mixture of 2 moles of helium gas atomic mass and 1 mole of argon gas atomic mass 40 amu is kept at 4 amu 300 K in a container The ratio of the rms speeds Vrms helium is Vims argon 2012 a 0 32 b 0 45 22 A real gas behaves like an idool c 2 24 d 3 16

A sound wave is propagating through a medium and the displacement equation for the particles of the medium is given by y Ao sin kx wt then which of the following options represents a possible pressure wave through this medium A AP sin kx wt BAP cos kx wt C AP cos kx wt D AP cos kx wt Solution B

47 A train is moving with 30 m s and speed of sound in air is 340 m s Another train is moving in opposite direction with speed 15 m s then apparent frequency genereted frequency by first train is 440 Hz and observer is in second train 1 458 Hz 2 450 Hz SPMT 04 08 4 490 Hz 3 503 Hz

IVE NUMERICAL A stationary source emits the sound of frequency fo 492 Hz The sound is reflected by a large car approaching the source with a speed of 2 ms The reflected signal is received by the source and superposed with the original What will be the beat frequency of the resulting signal in Hz Given that the speed of sound in air is 330 m s and the car reflects the sound at the frequency it has received

The intensity of the sound wave from a jet airplane as it is taking off is 106 W m at a distance of 6 10 m A person is standing at a distance of 120 m from the runway Assume that the sound wave radiates from the airplane equally in all directions At what rate does the jet airplane radiate energy in the form of sound waves

36 Two small speakers are separated by a distance of 5 cm as shown in Figure 33 44 The speakers are driven in phase with a sine wave signal of frequency 10 kHz A small microphone is placed a distance 1 m away from the speakers on the axis running through the middle of the two speakers and the microphone is then moved perpendicular to the axis Where does the microphone record the first minimum and the first maximum of the interference pattern from the speakers The speed of sound in air is 343 m s min 36 5cm 2 19 f 343m s 1 104 H 3 43x10 2m 3 43 cm dsino Microphone 5 cm Speakers max 94 3cm