Deck 14: Sound

Question 1

What is the speed of sound in air at a temperature of -110 ^$\circ$ F?

A)​279 m/s
B)​407 m/s
C)​256 m/s
D)​3 470 m/s

Answer 1

​279 m/s

Question 2

A sound wave coming from a tuba has a wavelength of 1.10 m and travels to your ears at a speed of 253 m/s.What is the frequency of the sound you hear?

A)278 Hz
B)1/278 Hz
C)230 Hz
D)1/230 Hz
E)​252 Hz

Answer 2

230 Hz

Question 3

The speed of sound at 0°C is 331 m/s.What is the speed of sound at 10.0°C? (0°C = 273 K)

A)337 m/s
B)325 m/s
C)324 m/s
D)329 m/s
E)​343 m/s

Answer 3

337 m/s

Question 4

A chamber that can be filled with different gases has placed in it a source of sound that in air produces a frequency of 200 Hz and a microphone to pick up the sound for frequency analysis.First the chamber is filled with helium (speed of sound 1 000 m/s at room conditions),then the helium is replaced with oxygen (speed of sound 330 m/s at room conditions),and then finally the helium is replaced with carbon dioxide (speed of sound 269 m/s at room conditions).In which gas is the highest frequency of sound found by the microphone during this experiment?

A)helium
B)oxygen
C)carbon dioxide
D)They all have the same frequency of sound.

Question 5

Material 1 has Young's modulus Y1 and density ρ1,material 2 has Young's modulus Y₂ and density ρ₂,and material 3 has Young's modulus Y3 and density ρ​₃.If Y1 > Y₂ > Y3 and if ρ1 < ρ2 < ρ​3,which material has the highest speed of sound?

A)material 1
B)material 2
C)material 3
D)They could all have equal speeds of sound.

Question 6

Which of the following ranges corresponds to the shortest wavelengths?

A)infrasonic
B)audible
C)ultrasonic
D)All have the same wavelengths.

Question 7

Comparing the speed of sound in liquids,gases,and solids,the speed of sound is usually lowest in ____ and highest in ____.

A)solids,liquids
B)gases,liquids
C)liquids,solids
D)gases,solids

Question 8

Material 1 has Young's modulus Y₁ and density ρ​₁,and material 2 has Young's modulus Y​₂ and density ρ₂.If Y₁ is 30% more than Y​₂ and ρ​₁ is 30% less than ρ₂,which material has the higher speed of sound and how much higher is it?

A)Material 1 has a speed of sound more than 35% higher than material 2.
B)Material 1 has a speed of sound 30% higher than material 2.
C)Material 2 has a speed of sound more than 80% higher than material 1.
D)Material 2 has a speed of sound 30% higher than material 1.

Question 9

When a sine wave is used to represent a sound wave,the crest corresponds to

A)rarefaction.
B)condensation.
C)point where molecules vibrate at a right angle to the direction of wave travel.
D)region of low elasticity.

Question 10

Consider a vibrating string that makes a sound wave that moves through the air.As the guitar string moves up and down,the air molecules that are a certain horizontal distance from the string will move

A)up and down.
B)toward and away from the guitar string.
C)back and forth along the direction of the length of the string.
D)in circles around the guitar string.

Question 11

When a sound wave moves through a medium such as air,the motion of the molecules of the medium is in what direction (with respect to the motion of the sound wave)?

A)perpendicular
B)parallel
C)anti-parallel (in opposite direction)
D)Both choices b and c are valid.

Question 12

How far away is a lightning strike if you hear the thunderclap 6.0 s after you see the lightning bolt strike? (v_sound = 340 m/s,v_light = 3.0 × 10⁸ m/s)

A)57 m
B)340 m
C)1 700 m
D)2 000 m
E)18 × 10⁸ m/s

Question 13

A series of ocean waves,7.0 m between crests,move past at 4.0 waves/s.Find their speed.

A)1.8 m/s
B)7.0 m/s
C)11.0 m/s
D)28 m/s
E)3.0 m/s

Question 14

Which of the following ranges corresponds to the longest wavelengths?

A)infrasonic
B)audible
C)ultrasonic
D)all have the same wavelengths

Question 15

​A sound wave has a frequency of 850 Hz.What is the sound wave's wavelength if the air temperature is 26.0 ^$\circ$ C?

A)​0.41 m
B)​2.0 m
C)​33 m
D)​0.42 m

Question 16

Assuming that the wave speed varies little when sound waves are traveling through a material that suddenly changes density by 10%,what percentage of the incident wave intensity is reflected?

A)< 1%
B)7.0%
C)10%
D)20%
E)25%

Question 17

A relatively new medical device that uses ultrasonics is referred to by the acronym CUSA.What does the letter A stand for?

A)aspirator
B)accumulator
C)array
D)audible

Question 18

The density of a certain metal solid is 6.5 × 10³ kg/m³,and its Young's modulus is 10.0 × 10¹⁰ N/m².What is the speed of sound in this metal?

A)8.1E+1 m/s
B)1.2E+3 m/s
C)3.9E+3 m/s
D)1.2E+5 m/s.
E)8.1E+1 m/s.

Question 19

The frequency separating audible waves and ultrasonic waves is considered to be 15.0 kHz.What wavelength in air at room temperature is associated with this frequency? (Assume the speed of sound to be 225 m/s. )

A)1.50 cm
B)33.8 cm..
C)22.5 cm
D)33.8 cm
E)​33.8 cm.

Question 20

The speed of sound in air is a function of which one of the following?

A)wavelength
B)frequency
C)temperature
D)amplitude

Question 21

In the afternoon,the decibel level of a busy freeway is 85 dB with 90 cars passing a given point every minute.Late at night,the traffic flow is only 8 cars per minute.What is the late-night decibel level?

A)200 dB
B)85 dB
C)170 dB
D)74 dB
E)8.5 dB

Question 22

If I₀ = 10−¹² W/m² is the threshold of hearing,a sound with intensity I₁ = 10−¹¹ W/m² will give a certain decibel level.Suppose a new sound has an intensity I₂ = 2I₁²/I₀.What is the new decibel level?

A)2.3 dB
B)23 dB
C)100 dB
D)it will square the decibel level
E)1.0 dB

Question 23

Tripling the distance between sound source and a listener will change the intensity,as detected by the listener,by what factor?

A)1/9
B)1/3
C)3
D)
E)9

Question 24

What sound level change corresponds to a factor of two change in intensity?

A)0.2 dB
B)2.0 dB
C)3.0 dB
D)11 dB
E)20 dB

Question 25

If one-third of the members of a symphony orchestra are absent because of head colds,thus reducing the overall intensity of sound by 33%,what will be the reduction in the decibel level?

A)15 dB
B)17 dB
C)11 dB
D)1.8 dB
E)4.1 dB

Question 26

A sound intensity of 70 dB is observed at a distance d from the source of sound.What sound intensity would be observed at a distance 2d from the source?

A)68 dB
B)67 dB
C)64 dB
D)62 dB

Question 27

If the distance between a point sound source and a dB detector is increased by a factor of 8,what will be the reduction in intensity level?

A)18 dB
B)0.016 dB
C)8 dB
D)65 dB
E)0.13 dB

Question 28

What is the intensity of a sound with a measured intensity level of 85 dB? (I₀ = 10−¹² W/m²)

A)1.3E-6 W/m²
B)3.2E-4 W/m²
C)8.5E-6 W/m²
D)2.0E-3 W/m²
E)​8.5E-3 W/m²

Question 29

By what amount does the sound intensity decrease when the distance to the source doubles?

A)1.4 dB
B)2 dB
C)4 dB
D)6.0 dB
E)0.25 dB

Question 30

Quadrupling the power output from a speaker emitting a single frequency will result in what increase in loudness?

A)17 dB
B)7.0 dB
C)6.0 dB
D)1.4 dB
E)​0.48 dB

Question 31

If the intensity of a sound is increased by a factor of 100,how is the decibel level changed? The new decibel level will be:

A)two units greater.
B)double the old one.
C)ten times greater.
D)twenty units greater.

Question 32

A source of sound has an intensity I​₁ and when its sound level is measured at a fixed distance the value found is 70 dB.The source then has its intensity increased to I​₂ and when its sound level is measured at the same distance the value found is 96 dB.What is the ratio ​I​₂/​I​₁?

A)26
B)400
C)600
D)14

Question 33

What is the intensity of sound from a band with a sound level of 129 dB? (I₀ = 10−¹² W/m²)

A)7.94 W/m²
B)1.29 W/m²
C)79.4 W/m²
D)12.9 W/m²
E)129 W/m²

Question 34

What is the intensity level of a sound with intensity of 6.0 × 10−¹⁰ W/m²? ( I₀ = 10−¹² W/m² )

A)20 dB
B)64 dB
C)2.8 dB
D)28 dB
E)​6.4 dB

Question 35

A very loud train whistle has an acoustic power output of 100 W.If the sound energy spreads out spherically,what is the intensity level in dB at a distance of 89.0 meters from the train? (I₀ = 10−¹² W/m²)

A)20.7 dB
B)70.0 dB
C)90.0 dB
D)95.0 dB
E)207 dB

Question 36

A speaker designed to emit spherical sound waves is producing a sound intensity of 8 W/m² at a distance of 1 m from the speaker.What would be the intensity of this sound at a distance of 2 m from the speaker?

A) W/m²
B)4 W/m²
C) W/m² ​
D)2 W/m²

Question 37

As a train starts from rest and then accelerates down the track,coming toward me faster and faster,the speed of the sound waves coming toward me will be

A)slower than the normal speed of sound in air.
B)equal to the normal speed of sound in air.
C)some constant speed faster than the normal speed of sound in air.
D)faster and faster.

Question 38

An iceberg breaks off from a glacier on the shore of the ocean with a loud cracking sound.the air.A person on a ship hears the sound in the water 4.0 s before hearing the sound in the air.How far away is the ship? The ambient temperature is -5.0 ^$\circ$ C.The speed of sound in saltwater is 1 530 m/s.

A)5 700 m
B)1 700 m
C)1 100 m
D)380 m

Question 39

​A common approximation is when the intensity of a sound is doubled,the decibel level increases by 3.The sound level in a particular location is 100 dB.By what approximate factor is the sound intensity increased if the new decibel level of this sound is 106?

A)​2
B)​3
C)​4
D)​6

Question 40

Which of the following best describes a sound level of intensity 1 W/m²?

A)extremely loud
B)about that of a power mower
C)normal conversation
D)like a whisper

Question 41

​An ambulance with its siren on is heading due east along a straight road at 60 mph.A car is also moving along the same road.In which case will the driver of the car perceive the frequency of the siren to be lowest?

A)​The car is moving east at 65 mph and is behind the ambulance
B)​The car is moving west at 65 mph and is behind the ambulance.
C)​The car is moving east at 65 mph and is in front of the ambulance.
D)​The car is moving west at 65 mph and is in front of the ambulance.

Question 42

A string of length L with fixed ends is made to go into standing wave patterns.What is the longest wavelength associated with all possible standing wave patterns in this situation?

A)L/4
B)L/2
C)L
D)2L

Question 43

If the tension on a guitar string is increased by a factor of 3,the fundamental frequency at which it vibrates is changed by what factor?

A)9
B)3
C)
D)1/
E)​1/3

Question 44

While standing at a crosswalk,you hear a frequency of 600 Hz from an approaching police car.After the police car passes,its frequency is 400 Hz.What is the speed of the police car? (speed of sound = 340 m/s)

A)34.0 m/s
B)60.0 m/s
C)66.3 m/s
D)68.0 m/s
E)199 m/s

Question 45

How many nodes does a standing wave in a string have at the frequency of the sixth harmonic?

A)12
B)6
C)3
D)The answer is not given.

Question 46

A 550-Hz whistle is moved toward a listener at a speed of 25.0 m/s.At the same time,the listener moves at a speed of 35.0 m/s in a direction away from the whistle.What is the apparent frequency heard by the listener? (The speed of sound is 340 m/s. )

A)510 Hz
B)533 Hz
C)655 Hz
D)460 Hz
E)594 Hz

Question 47

A buzzer with frequency f₀ is thrown straight upwards.On the buzzer's trip down,what is the frequency behavior heard by an observer below?

A)The frequency heard is still f₀.
B)The frequency is a constant one greater than f_0.
C)The frequency is an increasing one greater than f_0.
D)The frequency is a decreasing one less than f_0.

Question 48

Standing waves can result from _____ waves.

A)longitudinal
B)transverse
C)both longitudinal and transverse
D)neither longitudinal nor transverse

Question 49

When I stand halfway between two speakers,with one on my left and one on my right,a musical note from the speakers gives me constructive interference.How far to my left should I move to obtain destructive interference?

A)one-fourth of a wavelength
B)half a wavelength
C)one wavelength
D)one and a half wavelengths

Question 50

Two loudspeakers are placed side by side and driven by the same source at 525 Hz.A listener is positioned in front of the two speakers and on the line separating them,thus creating a constructive interference at the listener's ear.If one of the speakers is gradually pushed toward the listener,how far must it be moved to repeat the condition of constructive interference at the listener's ear? (The speed of sound = 340 m/s. )

A)1.5 m
B)0.65 m
C)0.32 m
D)0.16 m
E)3.1 m

Question 51

A sound source of frequency 1 100 Hz moves at 40.0 m/s toward a listener who is at rest.What is the apparent frequency heard by the listener? (speed of sound = 340 m/s)

A)1 230 Hz
B)970 Hz
C)980 Hz
D)1 250 Hz
E)870 Hz

Question 52

A bat,flying at 7.00 m/s toward a wall,emits a chirp at 50.0 kHz.If the wall reflects this sound pulse,what is the frequency of the echo received by the bat? (v_sound = 340 m/s)

A)52.1 kHz
B)51.1 kHz
C)50.0 kHz
D)49.0 kHz
E)48.6 kHz

Question 53

You stand by the railroad tracks as a train passes by.You hear a 1 020-Hz frequency when the train approaches,which changes to 760 Hz as it goes away.How fast is the train moving? The speed of sound in air is 340 m/s.

A)30.2 m/s
B)34.5 m/s
C)40.1 m/s
D)49.7 m/s
E)45.6 m/s

Question 54

A train station bell gives off a fundamental tone of 500 Hz as the train approaches the station at a speed of 30.0 m/s.If the speed of sound in air is 339 m/s,what will be the apparent frequency of the bell to an observer riding the train?

A)456 Hz
B)544 Hz
C)250 Hz
D)530 Hz
E)339 Hz

Question 55

The Doppler shift of ultrasonic waves can measure the speed of blood in an artery.If the frequency of the stationary source is 95.0 kHz and the reflected sound has a Doppler shift of 210 Hz,what is the blood flow speed? (The speed of sound inside the body is 1 500 m/s. )

A)1.0 m/s
B)1.7 m/s
C)3.3 m/s
D)3.9 m/s
E)6.5 m/s

Question 56

A plane is traveling at Mach 0.930 through air at a temperature of 0°C.What is the plane's speed? (Speed of sound at 0°C is 331 m/s. )

A)308 m/s
B)331 m/s
C)424 m/s
D)93.0 m/s
E)Mach number is undefined at 0°C.

Question 57

Two loudspeakers are placed next to each other and driven by the same source at 515 Hz.A listener is positioned in front of the two speakers and on the line separating them,thus creating a constructive interference at the listener's ear.What minimum distance would one of the speakers be moved back away from the listener to produce destructive interference at the listener's ear? (The speed of sound = 340 m/s. )

A)1.5 m
B)0.66 m
C)0.33 m
D)0.17 m
E)3.0 m

Question 58

Two cars,one in front of the other,are traveling down the highway at 55.0 m/s.The car behind sounds its horn,which has a frequency of 530 Hz.What is the frequency heard by the driver of the lead car? (v_sound = 340 m/s)

A)382 Hz
B)735 Hz
C)456 Hz
D)530 Hz
E)632 Hz

Question 59

An airplane flying with a constant speed flies from a warm air mass into a cold air mass.The Mach number will

A)increase.
B)decrease.
C)stay the same.
D)become unstable.

Question 60

When two sound waves are out of phase by ____,destructive interference will occur.

A)20°
B)120°
C)900°
D)720°
E)950°

Question 61

When the standing wave pattern in a pipe is NANA,the pipe has which of the following set of properties? (N stands for node,A for antinode. )

A)It is open at both ends.
B)It is closed at both ends.
C)It is open at one end and closed at the other end.
D)Any of the above could be true.

Question 62

A standing wave is set up in a 200-cm string fixed at both ends.The string vibrates in 8 distinct segments when driven by a 120-Hz source.What is the wavelength?

A)6 cm
B)13 cm
C)25 cm
D)50 cm
E)​100 cm

Question 63

The lower A on a piano has a frequency of 30.0 Hz.If the tension in the 2.00-m-long string is 316 N and one-half wavelength occupies the string,what is the mass of the string?

A)61.4 g
B)21.9 g
C)17.6 g
D)43.9 g
E)91.1 g

Question 64

If a guitar string has a fundamental frequency of 512 Hz,what is the frequency of its first overtone?

A)511 Hz
B)256 Hz
C)510 Hz
D)1 020 Hz
E)513 Hz

Question 65

A C note (f = 256 Hz)is sounded on a piano.If the length of the piano wire is 1.8 m and its mass density is 2.2 g/m,what is the tension in the wire?

A)6.4E+1 N
B)1.4E+2 N
C)1.9E+3 N
D)1.1E+3 N
E)5.6E+2 N

Question 66

What is the lowest frequency that will resonate in an organ pipe 5.00 m in length,closed at one end? The speed of sound in air is 340 m/s.

A)17.0 Hz
B)34.0 Hz
C)68.0 Hz
D)1 700 Hz
E)3 400 Hz

Question 67

A tuning fork is sounded above a resonating tube (one end closed),which resonates at a length of 0.40 m and again at 1.2 m.If the tube length were extended further,at what point will the tuning fork again create a resonance condition?

A)1.6 m
B)2.0 m
C)2.4 m
D)3.2 m
E)6.4 m

Question 68

A 2.5-m-long organ pipe is open at one end and closed at the other.Its fundamental tone has wavelength

A)1.3 m.
B)5.0 m.
C)10 m.
D)16 m.
E)2.5 m.

Question 69

A 1.30-m string is held fixed at both ends.When driven by a 140-Hz source,the string vibrates in 4 distinct segments.What is the natural fundamental frequency of the string?

A)35.0 Hz
B)70.0 Hz
C)215 Hz
D)431 Hz
E)45.5 Hz

Question 70

An astronaut sets up a pendulum on the Moon,where the acceleration due to gravity is 1/6 that of Earth.If she finds that she must push the pendulum with a frequency of 0.10 Hz to maintain a swinging motion,what is the length of the pendulum?

A)4.1 m
B)1.6 m
C)99 m
D)7.8 m

Question 71

A child sits on a swing supported by ropes of length 2.0 m.With what frequency will she need to apply the driving force to maintain swinging?

A)0.35 Hz
B)0.70 Hz
C)1.7 Hz
D)2.8 Hz
E)5.4 Hz

Question 72

Quintupling the tension in a guitar string will change its natural frequency by what factor?

A)
B)1
C)
D)5
E)5²

Question 73

A pipe is open at both ends.The distance from a node to its adjacent antinode is equal to _______.​

A)​0.25λ
B)​0.5λ
C)​1.25λ
D)​1.5λ

Question 74

A 90-m-long high-voltage cable is suspended between two towers.The mass of the 90-m cable is 100 kg.If the tension in the cable is 25 000 N,what is the lowest frequency at which this cable can oscillate?

A)0.83 Hz
B)1.00 Hz
C)1.7 Hz
D)2.00 Hz
E)3.3 Hz

Question 75

A string with fixed ends is made to go into standing wave patterns.At a given tension,the lowest frequency for which such a pattern exists is 150 Hz.Which of the following frequencies would also cause a standing wave pattern in this case?

A)250 Hz
B)500 Hz
C)750 Hz
D)All of the above frequencies will cause a standing wave pattern in this case.

Question 76

A note is being played on a string on a guitar.The string is then pushed to the side while still in contact with the same fret.What happens to the frequency of the note then played compared to the original note?

A)It is the same note since the same fret is being used.
B)It is at higher frequency than the original note.
C)It is at lower frequency than the original note.
D)It can be either higher of lower frequency depending on whether the original note was above or below middle C.

Question 77

If I quadruple the mass per unit length of guitar string,its natural frequency changes by what factor?

A)
B)1
C)
D)4
E)4²

Question 78

I stretch a rubber band and "plunk" it to make it vibrate in its fundamental frequency.I then stretch it to four times its length and make it vibrate in the fundamental frequency once again.The rubber band is made so that quadrupling its length quadruples the tension and reduces the mass per unit length by a factor of 4.The new frequency will be related to the old by a factor of

A)1.
B) .
C)4.
D)4².
E)1/4

Question 79

For a standing wave on a string the wavelength must equal

A)the distance between adjacent nodes.
B)the distance between adjacent antinodes.
C)twice the distance between adjacent nodes.
D)the distance between supports.

Question 80

Standing-wave vibrations are set up in a crystal wine glass with four nodes and four antinodes equally spaced around the 2.80-cm radius of the rim.If the resonant frequency of the glass is 8.50 kHz,what is the speed of the transverse waves moving around the glass?

A)1 500 m/s
B)748 m/s
C)374 m/s
D)238 m/s