# Quiz 17: Waves II

Physics & Astronomy

Q 1Q 1

The speed of a sound wave is determined by:
A)its amplitude
B)its intensity
C)its pitch
D)number of overtones present
E)the transmitting medium

Free

Multiple Choice

E

Q 2Q 2

The difference between transverse and longitudinal waves:
A)depends on the frequency of the wave
B)depends on the wavelength of the wave
C)depends on the direction of propagation of the wave
D)depends on the direction of oscillation of the medium relative to the direction of propagation of the wave
E)there is no difference, they are just two ways of describing the same phenomenon

Free

Multiple Choice

D

Q 3Q 3

What is a wavefront?
A)A set of points on a wave that are all traveling in the same direction.
B)The front of the wave is the highest point on the wave.
C)The front of the wave faces the direction the wave is traveling.
D)A set of points on a wave that all have the same wavelength.
E)A set of points on a wave that all have the same displacement.

Free

Multiple Choice

E

Q 4Q 4

The bulk modulus of water is 2.2 x 10

^{9}Pa, and its density is 1.0 x 10^{3}kg/m^{3}.What is the speed of sound in water? A)1.5 x 10^{3}m/s B)2.2 x 10^{3}m/s C)3.5 x 10^{3}m/s D)4.5 x 10^{3}m/s E)2.2 x 10^{6}m/sFree

Multiple Choice

Q 5Q 5

Take the speed of sound to be 340 m/s.A thunder clap is heard about 3 s after the lightning is seen.The source of both light and sound is:
A)moving overhead faster than the speed of sound
B)emitting a much higher frequency than is heard
C)emitting a much lower frequency than is heard
D)about 1000 m away
E)much more than 1000 m away

Free

Multiple Choice

Q 6Q 6

A sound wave has a wavelength of 3.0 m.The distance from a compression center to the adjacent rarefaction center is:
A)0.75 m
B)1.5 m
C)3.0 m
D)need to know wave speed
E)need to know frequency

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Multiple Choice

Q 7Q 7

Which of the following properties of a sound wave determine its "pitch"?
A)amplitude
B)distance form source to detector
C)frequency
D)phase
E)speed

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Multiple Choice

Q 8Q 8

The longitudinal displacement of a mass element in a medium as a sound wave passes through it is given by s = s

_{m}cos (kx - ωt).Consider a sound wave of frequency 440 Hz and wavelength 0.75m.If s_{m}= 12 µm, what is the displacement of an element of air located at x = 1.2 m at time t = 0.11 s? A)3.7 µm B)4.9 µm C)6.0 µm D)8.2 µm E)12 µmFree

Multiple Choice

Q 9Q 9

The longitudinal displacement of a mass element in a medium as a sound wave passes through it is given by s = s

_{m}cos (kx - ωt).Consider a sound wave of frequency 440 Hz and wavelength 0.75m.If s_{m}= 12 µm, how long does it take an element of air to move from a displacement of 12 µm to a displacement of 0 µm? A)0.57 ms B)1.1 ms C)2.3 ms D)3.4 ms E)4.6 msFree

Multiple Choice

Q 10Q 10

A fire whistle emits a tone of 170 Hz.Take the speed of sound in air to be 340 m/s.The wavelength of this sound is about:
A)0.5 m
B)1.0 m
C)2.0 m
D)3.0 m
E)340 m

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Multiple Choice

Q 11Q 11

During a time interval of exactly one period of vibration of a tuning fork, the emitted sound travels a distance:
A)equal to the length of the tuning fork
B)equal to twice the length of the tuning fork
C)of about 330 m
D)which decreases with time
E)of one wavelength in air

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Multiple Choice

Q 12Q 12

At points in a sound wave where the gas is maximally compressed, the pressure
A)is a maximum
B)is a minimum
C)is equal to the ambient value
D)is greater than the ambient value but less than the maximum
E)is less than the ambient value but greater than the minimum

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Multiple Choice

Q 13Q 13

The speed of sound in air is 340 m/s, and the density of air is 1.2 kg/m

^{3}.If the displacement amplitude of a 440-Hz sound wave is 10 µm, what is its pressure-variation amplitude? A)1.8 Pa B)3.3 Pa C)11 Pa D)15 Pa E)28 PaFree

Multiple Choice

Q 14Q 14

This graph shows the position of an element of air as a function of time as a sound wave passes through it.Which letter corresponds to the amplitude of the wave?
A)A
B)B
C)C
D)D
E)E

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Multiple Choice

Q 15Q 15

This graph shows the position of an element of air as a function of time as a sound wave passes through it.Which letter corresponds to the period of the wave?
A)A
B)B
C)C
D)D
E)E

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Multiple Choice

Q 16Q 16

Two small identical speakers are connected (in phase)to the same source.The speakers are 3 m apart and at ear level.An observer stands at X, 4 m in front of one speaker as shown.If the amplitudes are not changed, the sound he hears will be least intense if the wavelength is:
A)1 m
B)2 m
C)3 m
D)4 m
E)5 m

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Multiple Choice

Q 17Q 17

Two small identical speakers are connected (in phase)to the same source.The speakers are 3 m apart and at ear level.An observer stands at X, 4 m in front of one speaker as shown.The sound she hears will be most intense if the wavelength is:
A)5 m
B)4 m
C)3 m
D)2 m
E)1 m

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Multiple Choice

Q 18Q 18

Two sound waves are traveling through the same medium.They have the same amplitude, wavelength, and direction of travel.If the phase difference between them is 7π, the type of interference they exhibit is:
A)fully constructive
B)fully destructive
C)indeterminate
D)partially constructive
E)partially destructive

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Multiple Choice

Q 19Q 19

Two waves are out of phase by half a wavelength.What is this in radians?
A)π/6
B)π/4
C)π/2
D)π
E)3π/2

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Multiple Choice

Q 20Q 20

Two waves are out of phase by half a wavelength.What is this in degrees?
A)45°
B)90°
C)135°
D)180°
E)360°

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Multiple Choice

Q 21Q 21

The standard reference sound level is about:
A)the threshold of human hearing at 1000 Hz
B)the threshold of pain for human hearing at 1000 Hz
C)the level of sound produced when the 1 kg standard mass is dropped 1 m onto a concrete floor
D)the level of normal conversation
E)the level of sound emitted by a standard 60 Hz tuning fork

Free

Multiple Choice

Q 22Q 22

A microphone of surface area 2.0 cm

^{2}absorbs 1.1 mW of sound.What is the intensity of sound hitting the microphone? A)2.2 x 10^{-5}W/m^{2 }B)0.55 W/m^{2 }C)2.2 W/m^{2}D)2.8 W/m^{2}E)5.5 W/m^{2}Free

Multiple Choice

Q 23Q 23

The speed of sound in air is 340 m/s, and the density of air is 1.2 kg/m

^{3}.If the displacement amplitude of a 440-Hz sound wave is 10 µm, what is the intensity of the wave? A)0.16 W/m^{2}B)0.32 W/m^{2}C)12 W/m^{2}D)16 W/m^{2}E)32 W/m^{2}Free

Multiple Choice

Q 24Q 24

Consider two imaginary spherical surfaces of different radius, both centered on a point sound source emitting spherical waves.The power transmitted across the larger sphere is ________ the power transmitted across the smaller and the intensity at a point on the larger sphere is ________ the intensity at a point on the smaller.
A)greater than, the same as
B)greater than, greater than
C)greater than, less than
D)the same as, less than
E)the same as, the same as

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Multiple Choice

Q 25Q 25

The sound intensity 5.0 m from point source is 0.50 W/m

^{2}.The power output of the source is: A)12.5 W B)39 W C)79 W D)160 W E)260 WFree

Multiple Choice

Q 26Q 26

The sound level at a point P is 14 db below the sound level at a point 1.0 m from a point source.Assuming the intensity from a point source drops off like the inverse square of the distance, the distance from the source to point P is:
A)4.0 cm
B)20 m
C)2.0 m
D)5.0 m
E)25 m

Free

Multiple Choice

Q 27Q 27

The intensity of a certain sound wave is 6 W/cm

^{2}.If its intensity is raised by 10 decibels, the new intensity is: A)60 W/cm^{2}B)6.6 W/cm^{2}C)6.06 W/cm^{2}D)600 W/cm^{2}E)12 W/cm^{2}Free

Multiple Choice

Q 28Q 28

If I

_{0}= 10^{-12}W/m^{2}, and I = 4.5 x 10^{-8}W/m^{2}, what is log (I/I_{0})? A)4.5 x 10^{4}B)18 C)11 D)4.7 E)3.7Free

Multiple Choice

Q 29Q 29

The intensity of sound wave A is 100 times that of sound wave B.Relative to wave B the sound level of wave A is:
A)-2 db
B)+2 db
C)+10 db
D)+20 db
E)+100 db

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Multiple Choice

Q 30Q 30

If the sound level is increased by 10 db the intensity increases by a factor of:
A)2
B)5
C)10
D)20
E)100

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Multiple Choice

Q 31Q 31

You are listening to an "A" note played on a violin string.Let the subscript "s" refer to the violin string and "a" refer to the air.Then:
A)f

_{s}= f_{a}but _{s} _{a}_{ }B)f_{s}= f_{a}and _{s}= _{a}C)_{s}= _{a}but f_{s} f_{a}D)_{s} _{a}and f_{s} f_{a}E)linear density of string = volume density of airFree

Multiple Choice

Q 32Q 32

Two pipes are each open at one end and closed at the other.Pipe A has length L and pipe B has length 2L.Which harmonic of pipe B matches in frequency the fundamental of pipe A?
A)The fundamental
B)The second
C)The third
D)The fourth
E)There are none

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Multiple Choice

Q 33Q 33

An organ pipe with one end open and the other closed is operating at one of its resonant frequencies.The open and closed ends are respectively:
A)pressure node, pressure node
B)pressure node, displacement node
C)displacement antinode, pressure node
D)displacement node, displacement node
E)pressure antinode, pressure antinode

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Multiple Choice

Q 34Q 34

The "A" on a trumpet and a clarinet have the same pitch, but the two are clearly distinguishable.Which property is most important in enabling one to distinguish between these two instruments?
A)intensity
B)fundamental frequency
C)displacement amplitude
D)pressure amplitude
E)harmonic content

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Multiple Choice

Q 35Q 35

A standing wave in a pipe has nodes that are 1.2 m apart.What is the wavelength of the wave?
A)0.6 m
B)1.2 m
C)1.8 m
D)2.4 m
E)cannot tell without knowing which harmonic it is

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Multiple Choice

Q 36Q 36

A tuning fork produces sound waves of wavelength in air.This sound is used to cause resonance in an air column, closed at one end and open at the other.The length of this column CANNOT be:
A)/4
B)2/4
C)3/4
D)5/4
E)7/4

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Multiple Choice

Q 37Q 37

A column of argon is open at one end and closed at the other.The shortest length of such a column that will resonate with a 200 Hz tuning fork is 42.5 cm.The speed of sound in argon must be:
A)85.0 m/s
B)170 m/s
C)340 m/s
D)470 m/s
E)940 m/s

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Multiple Choice

Q 38Q 38

A 1024 Hz tuning fork is used to obtain a series of resonance levels in a gas column of variable length, with one end closed and the other open.The length of the column changes by 20 cm from resonance to resonance.From this data, the speed of sound in this gas is:
A)20 m/s
B)51 m/s
C)102 m/s
D)205 m/s
E)410 m/s

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Multiple Choice

Q 39Q 39

A vibrating tuning fork is held over a water column with one end closed and the other open.As the water level is allowed to fall, a loud sound is heard for water levels separated by 17 cm.If the speed of sound in air is 340 m/s, the frequency of the tuning fork is:
A)58 Hz
B)500 Hz
C)1000 Hz
D)2000 Hz
E)5800 Hz

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Multiple Choice

Q 40Q 40

Five organ pipes are described below.Which one has the highest fundamental frequency?
A)A 2.3-m pipe with one end open and the other closed
B)A 3.3-m pipe with one end open and the other closed
C)A 1.6-m pipe with both ends open
D)A 3.0-m pipe with both ends open
E)a pipe in which the displacement nodes are 5 m apart

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Multiple Choice

Q 41Q 41

If the speed of sound is 340 m/s, the two lowest frequencies of an 0.5 m organ pipe, closed at one end, are approximately:
A)170 and 340 Hz
B)170 and 510 Hz
C)340 and 680 Hz
D)340 and 1020 Hz
E)57 and 170 Hz

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Multiple Choice

Q 42Q 42

The lowest tone produced by a certain organ comes from a 3.0-m pipe with both ends open.If the speed of sound is 340 m/s, the frequency of this tone is approximately:
A)14 Hz
B)28 Hz
C)57 Hz
D)110 Hz
E)230 Hz

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Multiple Choice

Q 43Q 43

The speed of sound in air is 340 m/s.The shortest air column, closed at one end, which will resonate to a 512 Hz tuning fork is approximately:
A)4.2 cm
B)8.3 cm
C)17 cm
D)33 cm
E)66 cm

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Multiple Choice

Q 44Q 44

If the speed of sound is 340 m/s, the shortest pipe, closed at one end, which resonates at 218 Hz is:
A)39 cm
B)78 cm
C)1.6 m
D)3.1 m
E)6.2 m

Free

Multiple Choice

Q 45Q 45

Organ pipe Y (open at both ends)is twice as long as organ pipe X (open at one end)as shown.The ratio of their fundamental frequencies f

_{X:}:f_{Y}is: A)1:1 B)1:2 C)2:1 D)1:4 E)4:1Free

Multiple Choice

Q 46Q 46

A 200-cm organ pipe with one end open is in resonance with a sound wave of wavelength 270 cm.The pipe is operating in its:
A)fundamental frequency
B)first harmonic
C)second harmonic
D)third harmonic
E)fourth harmonic

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Multiple Choice

Q 47Q 47

An organ pipe with both ends open is 0.85 m long.Assuming that the speed of sound is 340 m/s, the frequency of the third harmonic of this pipe is:
A)200 Hz
B)300 Hz
C)400 Hz
D)600 Hz
E)none of these

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Multiple Choice

Q 48Q 48

The valves of a trumpet and the slide of a trombone are for the purpose of:
A)playing short (staccato)notes
B)tuning the instruments
C)changing the harmonic content
D)changing the length of the air column
E)producing gradations in loudness

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Multiple Choice

Q 49Q 49

Beats in sound occur when:
A)two waves of the same frequency interfere
B)two waves of slightly different frequency interfere
C)a reflected wave interferes with an incident wave
D)waves travel in two media having slightly different sound velocities
E)source and observer are in relative motion

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Multiple Choice

Q 50Q 50

To produce beats it is necessary to use two waves:
A)traveling in opposite directions
B)of slightly different frequencies
C)of equal wavelengths
D)of equal amplitudes
E)whose ratio of frequencies is an integer

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Multiple Choice

Q 51Q 51

In order for two sound waves to produce audible beats, it is essential that the two waves have:
A)the same amplitude
B)the same frequency
C)the same number of overtones
D)slightly different amplitudes
E)slightly different frequencies

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Multiple Choice

Q 52Q 52

The largest number of beats per second will be heard from which pair of tuning forks?
A)200 and 201 Hz
B)256 and 260 Hz
C)534 and 540 Hz
D)763 and 774 Hz
E)8420 and 8422 Hz

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Multiple Choice

Q 53Q 53

When listening to tuning forks of frequency 256 Hz and 260 Hz, one hears the following number of beats per second:
A)0
B)2
C)4
D)8
E)258

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Multiple Choice

Q 54Q 54

Two identical tuning forks vibrate at 256 Hz.One of them is then loaded with a drop of wax, after which 6 beats per second are heard.The frequency of the loaded tuning fork is:
A)250 Hz
B)253 Hz
C)256 Hz
D)259 Hz
E)262 Hz

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Multiple Choice

Q 55Q 55

Two identical strings, A and B, have nearly the same tension.When they both vibrate in their fundamental resonant modes, there is a beat of 3 Hz.When string B is tightened slightly, to increase the tension, the beat frequency becomes 6 Hz.This means:
A)that before tightening A had a higher frequency than B, but after tightening, B has a higher frequency than A
B)that before tightening B had a higher frequency than A, but after tightening, A has a higher frequency than B
C)that before and after tightening A has a higher frequency than B
D)that before and after tightening B has a higher frequency than A
E)none of the above

Free

Multiple Choice

Q 56Q 56

Two stationary tuning forks (350 and 352 Hz)are struck simultaneously.The resulting sound is observed to:
A)beat with a frequency of 2 beats/s
B)beat with a frequency of 351 beats/s
C)be loud but not beat
D)be Doppler shifted by 2 Hz
E)have a frequency of 702 Hz

Free

Multiple Choice

Q 57Q 57

The rise in pitch of an approaching siren is an apparent increase in its:
A)speed
B)amplitude
C)frequency
D)wavelength
E)number of overtones

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Multiple Choice

Q 58Q 58

The Doppler shift formula for the frequency detected is where f ' is the frequency emitted, v is the speed of sound, v

_{D}is the speed of the detector, and v_{s}is the speed of the source.Suppose the source is traveling at 5 m/s away from the detector, the detector is traveling at 7 m/s toward the source, and there is a 3 m/s wind blowing from the source toward the detector.The values that should be substituted into the Doppler shift equation are: A)v_{D}= 7 m/s and v_{s}= 5 m/s B)v_{D}= 10 m/s and v_{s}= 8 m/s C)v_{D}= 4 m/s and v_{s}= 2 m/s D)v_{D}= 10 m/s and v_{s}= 2 m/s E)v_{D}= 4 m/s and v_{s}= 8 m/sFree

Multiple Choice

Q 59Q 59

A stationary source generates 5.0 Hz water waves whose speed is 2.0 m/s.A boat is approaching the source at 1.0 m/s.The frequency of these waves, as observed by a person in the boat, is:
A)2.5 Hz
B)5.0 Hz
C)7.5 Hz
D)15 Hz
E)30 Hz

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Multiple Choice

Q 60Q 60

A stationary source S generates circular outgoing waves on a lake.The wave speed is 5.0 m/s and the crest-to-crest distance is 2.0 m.A person in a motor boat heads directly toward S at 3.0 m/s.To this person, the frequency of these waves is:
A)1.0 Hz
B)1.5 Hz
C)2.0 Hz
D)4.0 Hz
E)8.0 Hz

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Multiple Choice

Q 61Q 61

A stationary source emits a sound wave of frequency f.If it were possible for a man to travel toward the source at the speed of sound, he would observe the emitted sound to have a frequency of:
A)0
B)f/2
C)2f/3
D)2f
E)infinity

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Multiple Choice

Q 62Q 62

A source emits sound with a frequency of 1000 Hz.Both it and an observer are moving in the same direction with the same speed, 100 m/s.If the speed of sound is 340 m/s, the observer hears sound with a frequency of:
A)290 Hz
B)540 Hz
C)1000 Hz
D)1800 Hz
E)3400 Hz

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Multiple Choice

Q 63Q 63

A source emits sound with a frequency of 1000 Hz.It and an observer are moving toward each other, each with a speed of 100 m/s.If the speed of sound is 340 m/s, the observer hears sound with a frequency of:
A)290 Hz
B)540 Hz
C)1000 Hz
D)1800 Hz
E)3400 Hz

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Multiple Choice

Q 64Q 64

A source emits sound with a frequency of 1000 Hz.It is moving at 20 m/s toward a stationary reflecting wall.If the speed of sound is 340 m/s an observer at rest directly behind the source hears a beat frequency of:
A)3.0 Hz
B)55 Hz
C)63 Hz
D)114 Hz
E)118 Hz

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Multiple Choice

Q 65Q 65

In each of the following two situations a source emits sound with a frequency of 1000 Hz.In situation I the source is moving at 100 m/s toward an observer at rest.In situation II the observer is moving at 100 m/s toward the source, which is stationary.The speed of sound is 340 m/s.The frequencies heard by the observers in the two situations are:
A)I: 1417 Hz; II: 1294 Hz
B)I: 1417 Hz; II: 1417 Hz
C)I: 1294 Hz; II: 1294 Hz
D)I: 773 Hz; II: 706 Hz
E)I: 773 Hz; II: 773 Hz

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Multiple Choice

Q 66Q 66

The diagram shows four situations in which a source of sound S and a detector D are either moving or stationary.The arrows indicate the directions of motion.The speeds (when not zero)are all the same.(Note that the detector in situation 3 is stationary).Rank the situations according to the apparent frequency of the source, lowest to highest.
A)1, 2, 3, 4
B)4, 3, 2, 1
C)1, 3, 4, 2
D)2, 1, 4, 3
E)None of the above

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Multiple Choice

Q 67Q 67

A plane produces a sonic boom only when:
A)its speed changes from being slower than the speed of sound to being faster than the speed of sound
B)it emits sound waves of high frequency
C)it flies at high altitudes
D)it flies on a curved path
E)it flies faster than the speed of sound

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Multiple Choice

Q 68Q 68

If the speed of sound is 340 m/s a plane flying at 400 m/s has a Mach number of:
A)0.85
B)1.2
C)1.4
D)1.7
E)400

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Multiple Choice

Q 69Q 69

If the speed of sound is 340 m/s a plane flying at 400 m/s creates a conical shock wave with an apex half angle of:
A)0° (no shock wave)
B)32
C)40
D)50
E)58

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Multiple Choice

Q 70Q 70

The speed of sound is 340 m/s.A plane flies horizontally at an altitude of 10,000 m and a speed of 400 m/s.When an observer on the ground hears the sonic boom the horizontal distance from the point on its path directly above the observer to the plane is (assume the speed of sound does not change with altitude):
A)5800 m
B)6100 m
C)8400 m
D)12,000 m
E)16,000 m

Free

Multiple Choice