Sound Waves Questions and Answers

Sound travels about 750 miles per hour If you stand in a canyon and sound a horn you will hear an echo Round your answers to the nearest tenth as needed a Suppose it takes about 2 5 seconds to hear the echo How far away is the canyon wall in feet The canyon wall is feet away b Suppose you stand 550 feet from the canyon wall and sound the horn How long will it take to hear the echo It will take seconds to hear the echo

police car with its 300 Hz siren is moving away in the warehouse at a speed of 20 0 m s Part A What frequency does the driver of the police car hear reflected from the warehouse Use 344 m s for the speed of sound in air VAXO f GANG Hz

An iron block is dropped into a deep well Sound of splash is heard after 4 23 s If the depth of the well is Waves 105 78 4 m then find the speed of sound in air g 9 8 m s 1 300 m s 2 320 m s 3 280 m s 4 340 8 m s

HIFU U IV 3 12 On a transmission line with Z 50 the voltage at a distance 0 4A from the load is 4 j2 The corresponding current is 0 1 A Determine the norma ized load impedance Answer 0 145 j0 397

Two loudspeakers A and B are set up 2 80m apart from each other as shown in the diagram below The speakers are both emitting a frequency of 137 Hz A person standing directly in from of loudspeaker B begins walking away from the speaker There is only 1 location corresponding the the n 1 mode in front of speaker B where the 137 Hz signal will interfere constructively Part A What is the path difference at this location dp Submit Part B VAE Request Answer OO m 2 80 m B OO Ok

O A source of sound emitting frequency 256 Hz moves at 5m s towards a wall Find the beat frequency heard by an observer if the source is between the wall and the observer given the speed of sound is 330m s a 8 Hz b 10 Hz c 6 Hz d 12 Hz

3 A train moving at 80 miles hr sounds the whistle of frequency 400 Hz when 1 mile away from a railway crossing What is the frequency heard by an observer 0 6 miles from the crossing perpendicular to the railway track given the speed of sound in air is 0 2 mile s a 440 Hz b 441 Hz c 442 Hz d 444 Hz

Which of the following changes would increase the speed of sound in a gas medium a Increase in pressure b Decrease in density c Increasing the RMS speed of gas medium molecules d Using a gas of higher molar mass

A wire is tied between two walls separated by a distance of 50cm If the diameter of the wire is 1mm and tension in it is 100N The wire in its fundamental frequency produces 5 beats per second with a tuning fork If the tension in the wire is reduced to 81N the beat frequency does not change Find the frequency of the tuning fork b 90 Hz a 100 Hz c 95 Hz d 105 Hz

1 A sound source emits a frequency 1800 Hz and moves along a straight line at a distance 250m from a stationary observer If the speed of source is 0 8 times the speed of sound find the frequency heard by the observer when the source is closest to him a 4000 Hz b 2000 Hz c 5000 Hz d 3000 Hz

When a closed organ pipe of adjustable length is used consecutive resonance is observed with frequency of 2000 Hz at length 1 and 1 of the pipe If the difference of these lengths is 8 5cm find the speed of sound a 310m s b 320m s c 330m s d 340m s

Here it should be negative sign right Pls help 5 NORMAL MODES OF ORGAN PIPES Closed organ pipe only odd XX Seventh harmonic 5th Overtone Ninth harmonic 1 L n 2 for n 0 1 2 3 2L n 1 2 Possible wavelengths for n 0 1 2 3 Natural frequencies v n A MA XXX Secon First harmonic harmon First n for n 1 2 3 Over are proces n 2 1 1 for n or 0 1 2 3 2L Open Organ Pipe Eleventh harmonic Third armonic and overtone C

09 Two sound sources of same frequency are placed at distance of 100 meter An observer when moving between both sources hears 4 beats per second The distance between sound source is now changed to 400 meter then the beats second heard by observer 1 2 will be 2 4 3 8 4 16

Visible light of frequency f 4 832 10 4 Hz is beamed directly at a metal reflector Neglecting the refractive index of air a 5 points Find the wavelength of the visible light M b 10 points Determine the spacing between successive antinodes in the resulting standing wave pattern

A train is moving on a straight track with speed 20 ms It is blowing its whistle at the frequency of 1000 Hz The percentage change in the frequency heard by a person standing near the track as the train passes him is speed of sound 320 ms close to a 6 c 18 b 12 d 24 JEE Main 2015 th 20 m is suspended from a rigid

A table is revolving on its axis at 5 revolutions per second A sound source of frequency 1000 Hz is fixed on the table at 70 cm from the axis The minimum frequency heard by a listener standing at a distance from the table will be speed of sound 352 m s a 1000 Hz C 941 Hz Two sin b 1066 Hz d 352 Hz

Hz A source of sound of frequency f is placed on the ground A detector placed at 2 x 10 fi a height is released from rest on this source The observed frequency f Hz is plotted against time t sec The speed of sound in air is 300 m s Find f g 10 m s a 0 5 10 Hz c 0 25 10 A stationary b 1 10 Hz d 0 2 x 10 Hz Boy 30 1 5

The sound from a trumpet is emitted uniformly in all directions at 20 C At point P in space the sound intensity level is 30 dB The density of air in the medium is 1 5 kg m the velocity of sound at 20 C is 300 m sec If the displacement amplitude is A x 10 12 m at point P the frequency of sound wave in the medium is 600 Hz Write value of A Take n 10

Two passenger trains moving with a speed of 108 km hour cross each other One of them blows a whistle whose frequency is 750 Hz If sound speed is 330 m s then passengers sitting in the other train after trains cross each other will hear sound whose frequency will be a 900 Hz b 625 Hz c 750 Hz d 800 Hz A table is revolving on its ou

Let s try this 1 Take a small stone and a bucketful of water Drop the stone into the water from a height of about 20 cm You will hear the sound of the stone dropping in the water Now drop the same stone into the water from a height of about 100 cm You will hear its sound again What is the difference in the sounds in the two actions above What can we conclude from this 10

3v 10 A car is moving with a velocity towards a medium MNRP as shown where v is the speed of sound in air Two men A an B are moving towards each other in the medium with the velocities and respectively The speed of sound in medium is 7v and medium is kept at rest The car is emitting a sound of frequency f Then choose the correct option s N R The wavelength received by the man A is 49v 10f The wavelength received by the man A is different from the wavelength received by man B The ratio of frequency observed by the man A to that observed by the man B is 123 128 640 f

respectively a A f c 22 f 22 4 f d Both a and c Medium I b A sound wave propagating along x axis in medium I of density P 1 5 kg m is transmitted to a medium II of density p 3 kg m as shown Incident sound wave Medium II The equation of excess pressure developed by wave in medium I and that in medium II respectively are P 4x102 cos w t 500 1 P 3x102 cos w t a c X 400 B w A w Then the ratio of intensity of transmitted wave 1 wave in medium II to the intensity of incident wave I wave in medium I that is 12 is 1 32 X 1200 in SI units b in SI units 9 16 d None of these

11 A biker is moving with constant velocity v away from a long straight wall at an angle with the wall He honks a short beep of horn when he is at a distance I from the wall After how long from the instant he has honked will he again hear an echo of the honking Speed of the sound in air is c

77 Source and observer start moving simultaneously along x and y axis respectively The speed of source is twice the speed of observer vo If the ratio of observed frequency to the frequency of the source is 0 75 find the velocity of sound 11 a Vo S 16 Vo 5 0 c b d 17 5 19 75 vo Vo

1 Two sound waves emerging from a source reach a point simultaneously along two path of propagation when the path difference 55 cm the resultant intensity is zero at that point As the path difference gradually increases we get zero intensity next time when path difference is 77 cm If the speed of the sound of the sound is 330 m sec the frequency of the source is 1 500 Hz 3 1500 Hz 2 4 1000 Hz 2000 Hz

7 A bird is singing on a tree and a man is hearing at a distance r from the bird Calculate the displacement of the man towards the bird so that the loudness heard by the man increases by 20 dB 1 3 9r 10 3r 5 2 4 r 10 4r 5

Which of the following travelling wave will produc standing wave with node at x 0 whe superimposed y Asin wt kx 1 Asin wt kx 3 Acos wt kx 2 Asin wt kx d Acos wt kx

4 A whistle emits sound waves of frequency 2000 Hz These sound waves reach a point X through two different path such that path difference is 20 cm and there is silence at this point Y is a successive point at which also there is silence but the path difference is 35 cm Speed of sound is 1 340 m sec 2 300 m sec 3 380 m sec 4 332 m sec

A hammer strikes one end of a thick copper rail of length 8 12 m A microphone located at the opposite end of the rail detects two pulses of sound one that travels through the air and a longitudinal wave that travels through the rail The speed of sound in air is 343 m s b Find the separation in time between the arrivals of the two pulses

In expressing sound intensity we take 10 19 W m2 as the reference level For ordinary conversation the intensity level is about 106W m2 Expressed in decibel this is a 106 b 6 c 60 d log 10

3 The average density of Earth s crust 10 km beneath the surface is 2 7 gm cm The speed of longitudinal seismic waves at that depth is 5 4 km s The bulk modulus of Earth s crust considering its behaviour as fluid at that depth is a 7 9 x 10 0 Pa c 7 9 x 107 Pa b 5 6 x 10 0 Pa d 1 46 107 Pa

purce S receiver R and air are moving relative to the ground as shown in the fig Vs VR Vw 20 m s and velocity of sound in still air is 320m s If sourc erate sound of frequency 3600Hz then the frequency of sound received by the receiver will be Vw velocity of wind Vw

A person speaking normally produces a sound intensity of 40dB at distance of 1m If the threshold intensity for reasonable audibility is 20dB the maximum distance at which he can be heard clearly is 1 4m 3 10m 2 5m 4 20m

A sound source is moving towards a stationa 1 observer with of the speed of sound The rat 10 of apparent observed by observer to real observe by someone moving with the source wavelength sound is 11 1 10 2 2 11 10 2

The ratio of intensities between two coherent sound source is 4 1 The difference in loudness in decibels dB between maximum and minimum intensities when they interfere in space is 1 10 log2 2 20 log3 3 10 log3 4 20 log2

Three musicians experiment with the 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 fA on his trumpet B hears the note adjusts his trumpet and plays the same note he heard A B Question Type Multiple Correct Type u C 1 The note heard by C coming from B will be the same pitch as fa 2 The note heard by A coming from B will be higher in pitch than fa 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 be lower in pitch than f

Suppose there are 100 point sound sources with individual speed q arranged in a 10 X 10 square array the distance between the point sound sources is a and the body velocity is 180 degrees reverse a Try to find its far field sound pressure b Try to draw the far field radiation form when ka 1 IN 2

A stationary source of sound is emitting wave of frequency 30 Hz towards a stationary wall There is an observer standing between the source and the wall If the wind blows from the source to the wall with a speed 30 m s then the number of beats heard by the observer is velocity of sound with respect to wind is 330 m s Options 1 10 2 3 3 6 4 zero

A police van is chasing a thief s car on a straight highway with speed of van and car are 20 m s and 10 m s respectively If van is blowing horn of frequency 620 Hz then frequency heard by thief will be assume velocity of sound in air 330 m s 660 Hz X600 Hz 700 Hz 640 Hz

1 Beats are due to destructive interference X 2 Maximum beat frequency audible to a human being is 200 3 Beats are due to superposition of two wave of nearly equal frequencies X 4 Beats are produced as a result of Doppler s

Calculate the speed of sound in knots at a density altitude of 20 000 feet with an ambient pressure of 932 44 lb ft2 Note use the equations provided and the standard atmosphere table to obtain the speed of sound at sea level and the absolute temperature ratio 801 28 knots 701 28 knots

Two coherent light sources P and Q are at a distance 32 from each other as shown in the figure The distance from P on the x axis at which constructive interference may take place is y axis A 2 1 3 42 4 3 P x axis 2 32 4 22

7 a The mean optical power launched into an optical fiber having length a 5 km is 40 W and the mean optical power at receiver end is 4 W Calculate the signal attenuation per km of the fiber 5 5 Marks

b The signal retrieved in an optical fiber reduces at its output to one tenth of its input power What is the overall attenuation What shall be the power at output in a fiber having loss3 dB km

By providing 15kg wt one dinometer sn d one tuning fork has been ossulated to gether A prodece 8 beatsper second If tension increased to 16kg wt then tunin g fork produce unision with sonometer Frequency of tuning fork a 252Hz b 3 55Hz

The fundamental frequency of a closed organ pipe of length 20 cm is equal to the second overtone of an organ pipe open at both the ends The length of organ pipe open at both the ends is 140 cm 80 cm 12 50 hr min 100 cm

A tuning fork of known frequency 256 Hz makes 5 beats per second with the vibrating string of a piano The beat frequency decreases to 2 beats per second when the tension in the piano string is slightly increased The frequency of the piano string before increasing the tension was A 256 5Hz B O 256 2Hz C 256 2Hz

The variation of pressure for a sound wave travelling along the positive x axis is shown below Choose the correct statements Ap A B X A Particles just on left and right of point A are moving in opposite direction B Speed of particle on just left of A is less than that on right of A C Particles on just left and just right of B have opposite direction of motion D Particles on just left and just right of C are moving in same direction

As shown in the figure two loudspeakers are located at points A and B Both are vibrating in phase at a frequency and P and P2 are their respective powers Point C lies on a line joining two loudspeakers at a distance of di from A and d2 from B When both the speakers are switched on what is the resultant intensity in W m at point C Take velocity of sound 300 ms frequency 100Hz d 1 m and d 1 5 m P 8zW and P 18TW Also assume that loudspeakers behave like isotropic point sources emit sound uniformly in all directions A d d B

On a windless day sound emanate isotropically from a point source Rays of the sound waves emanated from a point source placed close to ground are shown in the figure Consider horizontal wind towards the left blowing with constant velocity which is uniform everywhere In the following figures rays of sound waves in presence of the wind are shown Which one is the most correct representation A B C D