Sound Waves Questions and Answers

A police car moving at 22 m s 1 chases a motor cycle The man in the car sounds his horn at 170 Hz while both of them move towards a stationary siren of frequency 165 Hz Calculate the speed of motor cycle if the motor cyclist does not listen any beat 22 m s

4 A police standing at a place detected a 10 change in frequency of the sound of a horn of a fast moving car approaching towards him If the velocity of sound is 340 m s what is the speed of the car 30 9 m s

A student while performing the experiment with a sonometer with bridges separated by a distance of 60 cm missed out some of the observations However he claimed that the three resonant frequencies for a given tuning fork were 84 140 and 224 Hz The speed of transverse wave in the wire is 33 60 m s 330 0 m s 44 80 m s 448 0 m s

A motor car is moving towards a vertical wall The driver observes that the frequency of the sound of his horn changes from 440 Hz to 480 Hz when he hears the reflected sound from the wall If the velocity of sound is 330 m s 1 what is the speed of the car ro Im h 11

Two sources separated by a certain distance are each producing a sound of frequency 1360 Hz A listener from the middle of the two sources starts moving towards a source If the number of beats heard by the listener per second is 4 calculate his speed Velocity of sound in air 340 m s 0 5 m s 1

3 A motor car blows a horn of frequency 1000 Hz while approaching a large reflector with a uniform velocity of 50 km h Calculate the frequency of the echo relative to the passenger of the car Velocity of sound 340 m s 1085 Hz

5 What will be the percentage difference between the frequency of the sound heard by an observer and the actual frequency of the whistle of a train approaching at a speed of 100 m s towards the observer Velocity of sound in air 330 m s 43 5

A sound wave passing through the air at NTP produces a pressure of 0 001 dyne cm2 during a compression The corresponding change in temperature given y 1 5 and assume gas to be ideal is 8 97 x 10 K 09 87 x 10 K C 8 97 x 10 K Serre

A tuning fork produces 4 beats per second with another tuning fork of frequency 256 Hz The first one is now loaded with very little wax and number of beats heard are 6 per second The original frequency of the tuning fork in Hz is 252 260 250

The second harmonic of an open organ pipe of length 10 cm and of radius of cross section 0 5 cm is equal to first overtone of a closed organ pipe of length cm and of same radius of cross section i e 0 5 cm Then which of the following is true 4 0 2 4 3 0 6 c 4 0 4 3 4 0 9

20 tuning forks are arranged in series in such a way that each fork gives 3 beats s with the previous one If the last fork is one octave lower of first fork then frequency of tenth fork is 187 Hz 3 92 Hz 2 89 Hz 4 84 Hz

In a closed organ pipe of length 105 cm standing waves are set up corresponding to third overtone What distance from the closed end a pressure node is formed 1 5 cm 3 25 cm 2 15 cm 4 30 cm

Assume that a police siren emits sound of wavelength 2 cm If an observer moving with a speed 20 m s approaches a stationary police jeep which with its siren switched on then the wavelength observed by the observer will be 0 5 m 1 cm 4 cm 2 cm

5 The ratio of intensities between two coherent sound sources is 4 1 The difference of loudness in dE between maximum and minimum intensities whe they interfere in the space is 1 20 log 0 3 3 20 log 0 2 2 10 log 0 2 4 10 log 0 3

A string of length 0 4 m and mass 10 2 kg is clamped at its ends The tension in the string is 1 6 N When a pulse travels along the string the shape of the string is found to be the same at times tand t At The value o Atis 0 05 s 0 1 s hr min 0 2 S

The amplitude of a wave disturbance propagating in positive x direction is given by 1 1 1 x 1 x 1 where y and x are in meter The speed of the wave is at time t 0 and y 2 m s 0 1 m s 0 4 m s 0 5 m s 2 at time t 2 seconds

A man stands somewhere between two cliffs When he claps his hand he hears two echoes one after 2 seconds and one after 4 seconds Taking the speed of sound as 300 m s find the distance between the cliffs 900 m 200 m hr miny 300 m

A tuning fork of frequency 400 Hz resonates with a tube closed at one end of length 20 cm and diameter 6 cm in fundamental mode The velocity of sound in air is 318 6 ms 1 332 8 ms 1 218 8 mc 1

If the pressure amplitude of a sound wave is increased by a factor of 4 then the average intensity increases by a factor of 8 2 hr m 4

4 vibratory string fixed at one end A tube of certain diameter and of length 48cm is open at both ends Its fundamental frequency of resonance is found to be 320Hz If velocity of sound in air is 320ms the diameter of the tube is 1 1 33cm 3 3 33cm 2 2 33cm 4 4 33cm

A source of sound is moving on a circular path with an angular speed of 4 rad s as shown The frequency of the source is 256 Hz The maximum frequency heared by a stationary observer at A is velocity of sound in air is 332 m s 265 6 Hz 242 4 Hz 296 5 Hz 3 m source Far off observer A

A car moves towards a hill with speed vc It blows a horn of frequency f which is heard by an observer following the car with speed vo The speed of sound in air is v The frequency of sound reaching the hill is The wavelength of sound reaching the hill is V V VC V Vc f The wavelength of sound of horn directly reaching the observer is The beat frequency observed by the observer is 2vc v Vo f v v V Vc f

O a musical instrument O the wavelength of noise O a musical note a measure of sound level

A man stands somewhere between two cliffs When h claps his hand he hears two echoes one after 2 seconds and one after 4 seconds Taking the speed of sound as 300 m s find the distance between the cliffs 900 m 200 m 300 m 100 m

Consider a cylindrical tube of length 240 cm which is closed at one end It is slowly filled with water such that the height of water in the tube increases at a rate of 2 cm s The rate of change of fundamental frequency when the water level in the tube is 120 cm is nearly Velocity of sound 340 m s 4 Hz s 2 Hz s 8 Hz s 1 Hz s

The second harmonic of an open organ pipe of length lo cm and of radius of cross section 0 5 cm is equal to first overtone of a closed organ pipe of length cm and of same radius of cross section i e 0 5 cm Then which of the following is true 4 c lo 0 2 4 c 3 0 6 Ic 4 0 4 31c 4l 0 9

A vibrating tuning fork is moving slowly and uniformly in a horizontal circular path of radius 8 m The shortest distance of an observer in same plane from the tuning fork is 9 m The distance between the tuning fork and observer at the instant when apparent frequency becomes maximum is 1 9 m 2 25 m 3 15 m 4 353 m

An open organ pipe 45 cm long and a closed organ pipe 38 cm long both of same diameter are each sounding their second overtone and are in unison The end correction of closed organ pipe is 0 75 cm 1 0 25 cm 3 1 cm 2 4 0 5 cm

In this figure shown BCD is an equilateral triangle of side length 1m A sound source of unknown frequency produce sound at A and minima is obtained at D The possible frequency of sound produced by source is speed of sound is 330 m s A 1 165 Hz 3 575 Hz D O 2 495 Hz 4 Both 1 and 2

of the following overtones of B is same as the fundamental frequency of A the strings are fixed at The tension length diameter and density of a string B are double than that of another string A Which both ends 1 1st 2 2nd A wire having a linear mass density 01 Kalm 3 3rd 4 4th topcion of 490 N It is observed that it

76 Wavelengths of two notes in air are 1 m and 1 1 164 Each note produces 1 beat s with a third note of a fixed frequency The speed of sound in air is a 330 m s b 340 m s c 350 m s d 328 m s m

27 A source of sound is moving towards a high wall with a speed of 25 m s A person moving away from the source and towards the wall with a velocity 5ms hears 5 beats sec The frequency of the sound produced by the source is velocity of sound 300 ms 1 a 250 Hz c 150 Hz b 300 Hz d 100 Hz

Three musicians experiment with the 16 Doppler effect Musician A rides in a car at a speed u directly away from musician B who is stationary Musician C rides in a car directly toward B and travels at the same speed as A Musician A plays a note at frequency f on his trumpet B hears the note adjusts his trumpet and plays the same note he heard Choose the incorrect statement u A B u C 1 The note heard by C coming from B will be the same pitch as f 2 The note heard by A coming from B will be higher in pitch than f 3 The note heard by A coming from B will be lower in pitch than f 4 The note heard by B coming from A will

39 An observer moves towards a stationary source of sound with a velocity one fifth of the velocity of sound The percentage increase in the apparent frequency is 1 5 2 20 3 zero 4 0 5

While measuring the speed of sound by performing a resonance column experiment a student gets the first resonance condition at a column length of 18 cm during winter Repeating the same experiment during summer she measures the column length to be x cm for the second resonance Then 2008 1 18 x 3 54 x 36 2 x 54 4 36 x 18

The total length of a sonometer wire between fixed ends is 110 cm Two bridges are placed to divide the length of wire in ratio 6 3 2 The tension in the wire is 400 N and the mass per unit length is 0 01 kg m What is the minimum common frequency with which three parts can vibrate 1 1100 Hz 2014 3 166 Hz 2 1000 Hz 4 100 Hz

A tuning fork with frequency 800 Hz produces resonance in a resonance column tube with upper end open and lower end closed by water surface Successive resonance are observed at lengths 9 75 cm 31 25 cm and 52 75 cm The speed of sound in air is NEET 2019 Odisha 1 172 m s 2 500 m s 3 156 m s 4 344 m s

A laser signal sent towards the moon returns after T seconds If C is the speed of light then the distance of the moon from the observer is given by A CT 2 C CT B CT 2 D 2CT

117 In a guitar two strings A and B made of same material are slightly out of tune and produce beats of frequency 6 Hz When tension in B is slightly decreased the beat frequency increases to 7 Hz If the frequency of A is 530 Hz the original frequency of B will be 530 H2 524 Hz 536 Hz 537 Hz 523 Hz 1 1 2 4 530 6 530 7

114 A boy is walking away from a fixed rigid wall at a speed of 1 m s in a direction at right angles to the wall As he walks he blows a whistle steadily An observer towards whom the boy is walking hears 4 beats per second if the speed of sound is 340 m s the true frequency of the whistle is A 340 Hz B 600 Hz C 680 Hz D 500 Hz

3 Two sound waves travel at a speed of 330 m s If their frequencies are also identical and are equal to 540 Hz what will be the phase difference between the waves at points 3 5 m from one source and 3 m from the other if the sources are in phase

Find the wrong statement from the following The relative speed between a source of sound and the observer is zero but the wind is blowing with a velocity Vw from the source to the observer In this case W a there is no change in the frequency of the sound heard b the velocity of sound is increased from V Vw c the wavelength of sound heard is decreased d the wavelength of sound heard is increased

Length of resonance tube is 150 cm Maximum level of liquid in resonance candition for wave having wavelength 80 cm is vi Length of resonance tube is 150 cm Minimum level of liquid in resonance candition for wave having wavelength 80 cm is

viii Length of OOP is 44 cm speed of sound 340 m s fundamental frequency is 340 Hz then value of end correction is Length of OOP is 38 cm speed of sound 340 m s fundamental frequency is 340 Hz then value of radius of pipe is

A tuning fork is found to give 20 beats in 12 seconds when sounded in conjuction with a stretched string vibrating under a tension of 14 4 or 10 kgf Calculate the frequency of the fork Two tuning fork n n produce two beats per sec n resonant with 15 cm COP and n resonant with

A sonometer wire emits a fundamental note of frequency 150 Hz Calculate the frequency of the note emite when the tension is changed in the ratio of 9 16 and length in the ratio of 1 2 with fourth harmonic of an open organ pipe find the

c y 3 sin 5x 0 5t 4 If OOP have 10 antinodes and fundamental freq 300 Hz then freq at 10th Antinode frequencies of COP s first overtone and OOP s second overtone is 180 find fundar

61 In the circuit shown here what is the value of the unknown resistor R so that the total resistance of the circuit between points P and Q is also equal to R 30 PMM a 32 c 69 92 www 32 10 Q www R b 39 92 d 10Q Q

D Two plane harmonic sound waves travelling in the same direction are given by the following displacement equations y x t A cos 0 5mx 100m y x t A cos 0 46xx 92nt How may times a listener can hear sound of maximum intensity in one second IIT 2006 a 8 c 4 b 6 d 3

If the intensity of sound is increased by a factor of 30 by how many decibels in the sound level increased 1 14 77 dB 2 14 50 dB 3 14 0 dB 4 None divid 141