# Quiz 14: Waves and Sound

Physics & Astronomy

Q 1Q 1

Give at least one example of each of the following:
(a) longitudinal standing wave.
(b) transverse standing wave.

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Essay

(a)sound wave resonating in an organ pipe (b)vibrating string on a violin

Q 2Q 2

A uniform rope hangs from a ceiling. Without tugging on the rope, you give the bottom of the rope a wiggle and a wave travels upward along the rope. What can you say about the speed of the wave as the wave travels up the rope?

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Essay

The speed increases because the tension is increasing.

Q 3Q 3

Write an expression for a harmonic wave that has an amplitude of 18 cm, a wavelength of 2.0 m, and propagates to the left at 15 m/s.

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Essay

y(x,t)= (18 cm)cos[(3.1 )x + (47 )t] or y(x,t)= (18 cm)cos[((2π/2.0) )x + ((2π × 7.5) )t]

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Short Answer

Q 5Q 5

In western movies you often see a person putting his ear against the rails in the train tracks to find out if a train is approaching. Why would this give him advance knowledge of the approach of a train?

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Essay

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True False

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True False

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True False

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True False

Q 10Q 10

FIGURE 14-1
-In Figure 14-1, the wavelength is
A) 8 m.
B) 4 m.
C) 2 m.
D) 1 m.
E) cannot be determined from the given information

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Multiple Choice

Q 11Q 11

FIGURE 14-1
-In Figure 14-1, the frequency is
A) 0.5 Hz.
B) 1 Hz.
C) 2 Hz.
D) 4 Hz.
E) cannot be determined from the given information

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Multiple Choice

Q 12Q 12

A wave pulse traveling to the right along a thin cord reaches a discontinuity where the rope becomes thicker and heavier. What is the orientation of the reflected and transmitted pulses?
A) Both are right side up.
B) The reflected pulse returns right side up while the transmitted pulse is inverted.
C) The reflected pulse returns inverted while the transmitted pulse is right side up.
D) Both are inverted.
E) It is impossible to predict.

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Multiple Choice

Q 13Q 13

Two strings are made of the same material. String 1 has radius r

_{1}while string 2 has radius r_{2}= r_{1}/2. When stretched by the same tension, the respective speed of propagation of waves v_{1}and v_{2}satisfy the condition A) v_{1}= v_{2}. B) v_{1}= 2v_{2}. C) v_{1}= v_{2}/ . D) v_{1}= v_{2}/2. E) v_{1}= v_{2}/4.Free

Multiple Choice

Q 14Q 14

Four waves are described by the following expressions, where distances are measured in meters and times in seconds. I y = 0.12 cos(3x - 21t)
II y = 0.15 sin(6x + 42t)
III y = 0.13 cos(6x + 21t)
IV y = -0.23 sin(3x - 42t)
Which of these waves travel in the +x direction?
A) I and II
B) I and III
C) II and IV
D) I and IV
E) II and III

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Multiple Choice

Q 15Q 15

Four waves are described by the following expressions, where distances are measured in meters and times in seconds. I y = 0.12 cos(3x - 21t)
II y = 0.15 sin(6x + 42t)
III y = 0.13 cos(6x + 21t)
IV y = -0.23 sin(3x - 42t)
Which of these waves have the same speed?
A) I and II
B) I and III
C) II and III
D) III and IV
E) II and IV

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Multiple Choice

Q 16Q 16

Four waves are described by the following expressions, where distances are measured in meters and times in seconds. I y = 0.12 cos(3x - 21t)
II y = 0.15 sin(6x + 42t)
III y = 0.13 cos(6x + 21t)
IV y = -0.23 sin(3x - 42t)
Which of these waves have the same period?
A) I and III, and also II and IV
B) I and IV, and also II and III
C) I and II, and also III and IV
D) All of them have the same period.
E) They all have different periods.

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Multiple Choice

Q 17Q 17

As the temperature of the air increases, what happens to the velocity of sound? (Assume that all other factors remain constant.)
A) It increases.
B) It decreases.
C) It does not change.
D) It increases when atmospheric pressure is high and decreases when the pressure is low.
E) It increases when atmospheric pressure is low and decreases when the pressure is high.

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Multiple Choice

Q 18Q 18

The pitch of a sound is determined by
A) the amplitude.
B) the speed.
C) the frequency.
D) the wavelength.
E) none of the above

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Multiple Choice

Q 19Q 19

Seven seconds after a brilliant flash of lightning, thunder shakes the house. How far was the lightning strike from the house?
A) Much closer than one kilometer
B) About one kilometer away
C) About two kilometers away
D) Much farther away than two kilometers
E) It is impossible to predict.

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Multiple Choice

Q 20Q 20

Sound vibrations with frequencies less than 20 Hz are called
A) infrasonics.
B) ultrasonics.
C) supersonics.
D) infrared.
E) megasonics.

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Multiple Choice

Q 21Q 21

Sound vibrations with frequencies greater than 20,000 Hz are called
A) infrasonics.
B) ultrasonics.
C) supersonics.
D) infrared.
E) megasonics.

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Multiple Choice

Q 22Q 22

Sound intensity is defined as
A) the loudness of a sound.
B) the sound energy passing through a unit of area.
C) the sound power per unit time.
D) the sound power per unit volume.
E) the sound energy passing through a unit of area per unit time.

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Multiple Choice

Q 23Q 23

By what amount does the intensity level decrease when you triple your distance from a source of sound?
A) 9.5 dB
B) 4.8 dB
C) 6.0 dB
D) 12 dB
E) 3.0 dB

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Multiple Choice

Q 24Q 24

By what amount does the intensity level increase when you triple the intensity of a source of sound?
A) 9.5 dB
B) 4.8 dB
C) 6.0 dB
D) 3.0 dB
E) 12 dB

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Multiple Choice

Q 25Q 25

The sound of 40 decibels is
A) twice as intense as the sound of 20 decibels.
B) four times as intense as the sound of 20 decibels.
C) 10 times as intense as the sound of 20 decibels.
D) 100 times as intense as the sound of 20 decibels.
E) 1000 times as intense as the sound of 20 decibels.

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Multiple Choice

Q 26Q 26

The reason that you do not observe a Doppler shift when you listen to the car radio while driving is that
A) the source and observer are moving at the same speed.
B) the air inside the car is moving at the same speed as the car.
C) the speed of the car is too slow compared to the speed of sound.
D) the speed of the car is too fast compared to the speed of sound.
E) there is a Doppler shift but we don't notice it.

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Multiple Choice

Q 27Q 27

A sound source approaches a stationary observer. The frequency heard by the observer is
A) higher than the source.
B) lower than the source.
C) the same as that of the source.
D) equal to zero.
E) impossible to predict.

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Multiple Choice

Q 28Q 28

A sound source departs from a stationary observer. The frequency heard by the observer is
A) higher than the source.
B) lower than the source.
C) the same as that of the source.
D) equal to zero.
E) impossible to predict.

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Multiple Choice

Q 29Q 29

Two cars are traveling in the same direction and with the same speed along a straight highway. Does either driver hear a different frequency from the other car's horn than they would if the cars were stationary?
A) Yes, they both experience a Doppler shift.
B) Only the driver of the front car experiences a Doppler shift.
C) Only the driver of the rear car experiences a Doppler shift.
D) No, because neither driver experiences a Doppler shift.
E) It is impossible to predict.

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Multiple Choice

Q 30Q 30

In many cartoon shows, a character runs of a cliff, realizes his predicament and lets out a scream. He continues to scream as he falls. If the physical situation is portrayed correctly, from the vantage point of an observer at the top of the cliff leaning over the edge, the pitch of the scream should be
A) higher than the original pitch and constant.
B) higher than the original pitch and increasing as he falls.
C) lower than the original pitch and constant.
D) lower than the original pitch and decreasing as he falls.
E) It is impossible to predict.

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Multiple Choice

Q 31Q 31

In many cartoon shows, a character runs of a cliff, realizes his predicament and lets out a scream. He continues to scream as he falls. If the physical situation is portrayed correctly, from the vantage point of an observer at the foot of the cliff, the pitch of the scream should be
A) higher than the original pitch and constant.
B) higher than the original pitch and increasing as he falls.
C) lower than the original pitch and constant.
D) lower than the original pitch and decreasing as he falls.
E) It is impossible to predict.

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Multiple Choice

Q 32Q 32

Car 1 moves toward car 2 with speed v. An observer in car 2 measures the frequency of the sound emitted by car 1's horn to be f. Now, car 1 remains stationary while car 2 moves toward car 1 with speed v. The observer in car 2 now measures the frequency of car 1's horn to be f'. The relationship between the observed frequencies is
A) f < f'.
B) f = f'.
C) f = 2 f'.
D) f = 1/2 f'.
E) f > f'.

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Multiple Choice

Q 33Q 33

Two wave pulses with equal positive amplitudes pass each other on a string. One is traveling toward the right and the other toward the left. At the point that they occupy the same region of space at the same time
A) constructive interference occurs.
B) destructive interference occurs.
C) a standing wave is produced.
D) a traveling wave is produced.

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Multiple Choice

Q 34Q 34

Two wave pulses pass each other on a string. The one traveling toward the right has a positive amplitude, while the one traveling toward the left has an equal amplitude in the negative direction. At the point that they occupy the same region of space at the same time
A) constructive interference occurs.
B) destructive interference occurs.
C) a standing wave is produced.
D) a traveling wave is produced.

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Multiple Choice

Q 35Q 35

The wavelengths corresponding to the harmonics of a string with fixed ends can be found by saying that the length of the string must be equal to
A) an odd number of quarter-wavelengths.
B) an odd number of third-wavelengths.
C) an odd number of half-wavelengths.
D) an integer number of half-wavelengths.
E) an integer number of wavelengths.

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Multiple Choice

Q 36Q 36

The wavelengths corresponding to the harmonics of an organ pipe that is open at one end and closed at the other can be found by saying that the length of the pipe must be equal to
A) an odd number of quarter-wavelengths.
B) an odd number of third-wavelengths.
C) an odd number of half-wavelengths.
D) an integer number of half-wavelengths.
E) an integer number of wavelengths.

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Multiple Choice

Q 37Q 37

Which part of a vibrating string experiences the maximum acceleration?
A) nodes
B) ends
C) antinodes

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Multiple Choice

Q 38Q 38

In a resonating pipe which is open at both ends, there
A) are displacement nodes at each end.
B) are displacement antinodes at each end.
C) is a displacement node at one end and a displacement antinode at the other end.
D) none of the above

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Multiple Choice

Q 39Q 39

Consider an open pipe of length L. What are the wavelengths of the three lowest tones produced by this pipe?
A) 16L, 4L, L
B) 4L, 2L, L
C) 2L, L, L/2
D) 2L, L, 2L/3
E) 4L, 4L/3, 4L/5

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Multiple Choice

Q 40Q 40

An open pipe of length L is resonating at its fundamental frequency. Which statement is correct?
A) The wavelength is 2L and there is a displacement node at the pipe's midpoint.
B) The wavelength is 2L and there is a displacement antinode at the pipe's midpoint.
C) The wavelength is L and there is a displacement node at the pipe's midpoint.
D) The wavelength is L and there is a displacement antinode at the pipe's midpoint.
E) The wavelength is 3L/2 and there are two displacement antinodes located inside the pipe.

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Multiple Choice

Q 41Q 41

In a resonating pipe which is open at one end and closed at the other, there
A) are displacement nodes at each end.
B) are displacement antinodes at each end.
C) is a displacement node at the open end and a displacement antinode at the closed end.
D) is a displacement node at the closed end and a displacement antinode at the open end.

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Multiple Choice

Q 42Q 42

Consider a closed pipe of length L. What are the wavelengths of the three lowest tones produced by this pipe?
A) 16L, 4L, L
B) 4L, 2L, L
C) 2L, L, L/2
D) 2L, L, 2L/3
E) 4L, 4L/3, 4L/5

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Multiple Choice

Q 43Q 43

A pipe of length L closed at one end is resonating at its fundamental frequency. Which statement is correct?
A) The wavelength is 4L and there is a displacement node at the pipe's open end.
B) The wavelength is 4L and there is a displacement antinode at the pipe's open end.
C) The wavelength is L and there is a displacement node at the pipe's open end.
D) The wavelength is L and there is a displacement antinode at the pipe's open end.

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Multiple Choice

Q 44Q 44

In order to produce beats, the two sound waves should have
A) the same amplitude.
B) slightly different amplitudes.
C) the same period.
D) the same frequency.
E) slightly different frequencies.

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Multiple Choice

Q 45Q 45

Two pure tones are sounded together and a particular beat frequency is heard. What happens to the beat frequency if the frequency of one of the tones is increased?
A) It increases.
B) It decreases.
C) It does not change.
D) It becomes zero.
E) It could either increase or decrease.

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Multiple Choice

Q 46Q 46

In the open ocean, the tides are waves that have a period of 12 hours and a speed of 750 km/hr. What is their wavelength?

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Short Answer

Q 47Q 47

An elephant can hear sound with a frequency of 15.0 Hz. What is the wavelength of this wave?
The speed of sound in air is 343 m/s.

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Short Answer

Q 48Q 48

A ten-year exposure to the sound of a riveting machine will cause your threshold of hearing to shift from 0 dB to 30 dB. What is the sound intensity corresponding to 30 dB?
The normal lowest detectable intensity is 1.0 × 10

^{-12}W/m^{2}.Free

Short Answer

Q 49Q 49

If the intensity level of one trombone is 70 dB and that of one cornet is 65 dB, which is louder:
76 trombones or 110 cornets?

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Short Answer

Q 50Q 50

A factory siren indicating the end of a shift has a frequency of 90.0 Hz.
(a) What frequency is perceived by the occupant of a car traveling towards the factory at 25 m/s?
(b) What frequency is perceived by the occupant of a car traveling away from the factory at 30 m/s?

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Short Answer

Q 51Q 51

Two in-phase loudspeakers are placed along a wall and are separated by a distance of 4.00 m. They emit sound with a frequency of 514 Hz. A person is standing away from the wall, in front of one of the loudspeakers.
(a) What is the closest distance from the wall the person can stand and hear constructive interference?
(b) What is the closest distance from the wall the person can stand and hear destructive interference?

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Short Answer

Q 52Q 52

A harmonic wave has a wavelength of 2.0 m and a frequency of 5.0 Hz. What is the speed of the wave?
A) 10 m/s
B) 0.40 m/s
C) 0.50 m/s
D) 0.10 m/s
E) 2.5 m/s

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Multiple Choice

Q 53Q 53

A harmonic wave travels with a speed of 200 m/s and has a wavelength of 0.800 m. What is the frequency of the wave?
A) 25.0 Hz
B) 40.0 Hz
C) 125 Hz
D) 80.0 Hz
E) 250 Hz

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Multiple Choice

Q 54Q 54

A fisherman fishing from a pier observes that the float on his line bobs up and down, taking 2.4 s to move from its highest to its lowest point. He also estimates that the distance between adjacent wave crests is 48 m. What is the speed of the waves going past the pier?
A) 1.0 m/s
B) 20 m/s
C) 10 m/s
D) 5.0 m/s
E) 115 m/s

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Multiple Choice

Q 55Q 55

A tsunami, an ocean wave generated by an earthquake, propagates along the open ocean at 700 km/hr and has a wavelength of 750 km. What is the frequency of the waves in such a tsunami?
A) 0.933 Hz
B) 0.000259 Hz
C) 1.07 Hz
D) 6.76 Hz
E) 0.148 Hz

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Multiple Choice

Q 56Q 56

The speed of surface waves in deep water is given by v = gT/2π. What is the wavelength of a wave that has a period of 3.00 s?
A) 4.68 m
B) 29.4 m
C) 14.1 m
D) 44.1 m
E) 39.4 m

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Multiple Choice

Q 57Q 57

A 6.00-m length of rope has a mass of 700 g. It is pulled taught with a force of 100 N. What is the speed of waves on the rope?
A) 29.3 m/s
B) 11.7 m/s
C) 42.0 m/s
D) 3.42 m/s
E) 4.20 m/s

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Multiple Choice

Q 58Q 58

A 15.0-m rope is pulled taut with a tension of 140 N. It takes 0.545 s for a wave to propagate along the rope. What is the mass of the rope?
A) 1.67 kg
B) 2.10 kg
C) 2.77 kg
D) 5.09 kg
E) 3.19 kg

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Multiple Choice

Q 59Q 59

Two steel wires are stretched with the same tension. The first wire has a diameter of 0.610 mm and the second wire has a diameter of 0.910 mm. If the speed of waves traveling along the first wire is 54.0 m/s, what is the speed of waves traveling along the second wire?
A) 24.9 m/s
B) 27.2 m/s
C) 36.2 m/s
D) 81.0 m/s
E) 100 m/s

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Multiple Choice

Q 60Q 60

What is the wave speed in a brass wire with a radius of 0.500 mm stretched with a tension of 125 N? The density of brass is 8.60 × 10

^{3}kg/m^{3}. A) 0.121 m/s B) 100 m/s C) 136 m/s D) 500 m/s E) 68.8 m/sFree

Multiple Choice

Q 61Q 61

The wave speed in an aluminum wire with a radius of 1.00 mm is 120 m/s. What is the tension in the wire? The density of aluminum is 2.70 × 10

^{3}kg/m^{3}. A) 112 N B) 100 N C) 134 N D) 427 N E) 122 NFree

Multiple Choice

Q 62Q 62

The vertical displacement of a string is given by y(x,t) = (6.00 mm) cos[(3.25 m

^{-1})x - (7.22 s^{-1})t]. What is the wavelength of the wave? A) 3.25 m B) 1.93 m C) 0.870 m D) 0.308 m E) 0.139 mFree

Multiple Choice

Q 63Q 63

The vertical displacement of a string is given by y(x,t) = (6.00 mm) cos[(3.25 m

^{-1})x - (7.22 s^{-1})t]. What is the period of the wave? A) 7.22 s B) 1.93 s C) 0.870 s D) 0.308 s E) 0.139 sFree

Multiple Choice

Q 64Q 64

The vertical displacement of a string is given by y(x,t) = (6.00 mm) cos[(3.25 m

^{-1})x - (7.22 s^{-1})t]. What is the speed of the wave? A) 0.450 m/s B) 1.41 m/s C) 2.22 m/s D) 3.16 m/s E) 23.5 m/sFree

Multiple Choice

Q 65Q 65

The vertical displacement of a string is given by y(x,t) = (6.00 mm) cos[(3.25 m

^{-1})x - (7.22 s^{-1})t]. What is the amplitude of the wave? A) 6.00 mm B) 12.0 mm C) 3.00 mm D) 2.00 mm E) None of the other choices is correct.Free

Multiple Choice

Q 66Q 66

You drop a stone down a well that is 9.50 m deep. How long is it before you hear the splash? The speed of sound in air is 343 m/s.
A) 1.39 s
B) 1.40 s
C) 1.41 s
D) 1.42 s
E) 1.43 s

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Multiple Choice

Q 67Q 67

You drop a stone down a well. You hear the splash 1.63 s later. How deep is the well? The speed of sound in air is 343 m/s.
A) 6.96 m
B) 20.2 m
C) 12.5 m
D) 18.8 m
E) 20.0 m

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Multiple Choice

Q 68Q 68

The speed of sound through the ground is about 6.0 km/s while the speed of sound in air is 343 m/s. A very powerful explosion occurs some distance away and you feel the ground vibrate 60 seconds before you hear the sound of the explosion. How far away is the explosion?
A) 20 km
B) 22 km
C) 25 km
D) 27 km
E) 30 km

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Multiple Choice

Q 69Q 69

An earthquake generates three kinds of waves: surface waves (L-waves), which are the slowest and weakest, shear (S) waves, which are transverse waves and carry most of the energy, and pressure (P) waves, which are longitudinal waves and are the fastest. The speed of P waves is approximately 7 km/s, and that of S waves is about 4 km/s. People do not generally feel the P waves, but animals seem to be sensitive to them. If a person reports that her dog started barking 20 seconds "before the earthquake," then approximately how far was the origin of the earthquake?
A) 100 km
B) 200 km
C) 300 km
D) 400 km
E) 500 km

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Multiple Choice

Q 70Q 70

Two people are talking at a distance of 3.0 m from where you are and you measure the sound intensity as 1.1 × 10

^{-7}W/m^{2}. Another student is 4.0 m away from the talkers. What sound intensity does the other student measure? A) 6.2 × 10^{-8}W/m^{2}B) 1.5 × 10^{-7}W/m^{2}C) 8.3 × 10^{-8}W/m^{2}D) 7.8 × 10^{-7}W/m^{2}E) 2.5 × 10^{-8}W/m^{2}Free

Multiple Choice

Q 71Q 71

A crying baby emits sound with an intensity of 8.0 × 10

^{-8}W/m^{2}. What is the intensity level for a set of quintuplets? The lowest detectable intensity is 1.0 × 10^{-12}W/m^{2}. A) 79 dB B) 69 dB C) 56 dB D) 49 dB E) 36 dBFree

Multiple Choice

Q 72Q 72

The intensity level of a power mower at a distance of 1.0 m is 100 dB. You wake up one morning to find that four of your neighbors are mowing their lawn 20 m from your open bedroom window. What is the intensity level in your bedroom?
A) 80 dB
B) 104 dB
C) 400 dB
D) 50 dB
E) 40 dB

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Multiple Choice

Q 73Q 73

If the intensity level of one trombone is 70 dB, what is the intensity level of 76 trombones?
A) 146 dB
B) 89 dB
C) 70 dB
D) 76 dB
E) 82 dB

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Multiple Choice

Q 74Q 74

A car horn emits a frequency of 400 Hz. A car traveling at 20.0 m/s sounds the horn as it approaches a stationary pedestrian. What frequency does the pedestrian hear? The speed of sound in air is 343 m/s.
A) 200 Hz
B) 375 Hz
C) 400 Hz
D) 425 Hz
E) 450 Hz

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Multiple Choice

Q 75Q 75

A factory siren indicating the end of a shift has a frequency of 80 Hz. What frequency is perceived by the occupant of a car traveling towards the factory at 30 m/s? The speed of sound in air is 343 m/s.
A) 83 Hz
B) 85 Hz
C) 87 Hz
D) 89 Hz
E) 91 Hz

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Multiple Choice

Q 76Q 76

A car horn emits a frequency of 400 Hz. A car traveling at 20.0 m/s sounds the horn as it goes away from a stationary pedestrian. What frequency does the pedestrian hear? The speed of sound in air is 343 m/s.
A) 378 Hz
B) 389 Hz
C) 411 Hz
D) 422 Hz
E) 450 Hz

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Multiple Choice

Q 77Q 77

A factory siren indicating the end of a shift has a frequency of 80 Hz. What frequency is perceived by the occupant of a car traveling away from the factory at 30 m/s? The speed of sound in air is 343 m/s.
A) 73 Hz
B) 75 Hz
C) 77 Hz
D) 79 Hz
E) 81 Hz

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Multiple Choice

Q 78Q 78

A car approaches you at a constant speed, sounding its horn, and you hear a frequency of 76 Hz. After the car goes by, you hear a frequency of 65 Hz. What is the frequency of the sound emitted by the horn? The speed of sound in air is 343 m/s.
A) 68 Hz
B) 69 Hz
C) 70 Hz
D) 71 Hz
E) 72 Hz

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Multiple Choice

Q 79Q 79

As you stand by the side of the road, a car approaches you at a constant speed, sounding its horn, and you hear a frequency of 76 Hz. After the car goes by, you hear a frequency of 65 Hz. What is the speed of the car? The speed of sound in air is 343 m/s.
A) 26 m/s
B) 27 m/s
C) 28 m/s
D) 29 m/s
E) 30 m/s

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Multiple Choice

Q 80Q 80

You are driving along a highway at 35.0 m/s when you hear the siren of a police car approaching you from behind and you perceive the frequency as 1340 Hz. You are relieved that he is in pursuit of a different speeder when he continues past you, but now you perceive the frequency as 1300 Hz. What is the speed of the police car? The speed of sound in air is 343 m/s.
A) 38.4 m/s
B) 30 m/s
C) 39.2 m/s
D) 40.1 m/s
E) 41.7 m/s

Free

Multiple Choice

Q 81Q 81

You are driving along a highway at 35.0 m/s when you hear the siren of a police car approaching you from behind and you perceive the frequency as 1310 Hz. You are relieved that he is in pursuit of a different speeder when he continues past you, but now you perceive the frequency as 1240 Hz. What is the frequency of the siren in the police car? The speed of sound in air is 343 m/s.
A) 1300 Hz
B) 1320 Hz
C) 1270 Hz
D) 1360 Hz
E) 1370 Hz

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Multiple Choice

Q 82Q 82

You are driving along a highway at 25 m/s when you hear the siren of an emergency vehicle traveling in the opposite direction on the other side of the highway. When the vehicle is approaching you, you hear the frequency of the siren as 2380 Hz, but when it is past you the frequency becomes 1680 Hz. What is the speed of the vehicle? The speed of sound in air is 343 m/s.
A) 35 m/s
B) 32 m/s
C) 30 m/s
D) 41 m/s
E) 50 m/s

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Multiple Choice

Q 83Q 83

You are driving along a highway at 25.0 m/s when you hear the siren of an emergency vehicle traveling in the opposite direction on the other side of the highway. When the vehicle is approaching you, you hear the frequency of the siren as 2380 Hz, but when it is past you the frequency becomes 1680 Hz. What is the frequency of the siren? The speed of sound in air is 343 m/s.
A) 1850 Hz
B) 2000 Hz
C) 2050 Hz
D) 2010 Hz
E) 1980 Hz

Free

Multiple Choice

Q 84Q 84

Two in-phase loudspeakers are 3.00 m apart. They emit sound with a frequency of 490 Hz. A microphone is placed half-way between the speakers and then moved along the line joining the two speakers until the first point of constructive interference is found. At what distance from that midpoint is that first point? The speed of sound in air is 343 m/s.
A) 0.175 m
B) 0.350 m
C) 0.500 m
D) 0.700 m
E) There is no point in that line where constructive interference occurs.

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Multiple Choice

Q 85Q 85

Two in-phase loudspeakers are some distance apart. They emit sound with a frequency of 572 Hz. A microphone is moved between the speakers to record the wave amplitude at points along that line. What is the spacing between points where constructive interference occurs? The speed of sound in air is 343 m/s.
A) 0.300 m
B) 0.600 m
C) 0.900 m
D) 1.20 m
E) 1.50 m

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Multiple Choice

Q 86Q 86

Two in-phase loudspeakers are placed along a wall and are separated by a distance of 4.00 m. They emit sound with a frequency of 514 Hz. A person is standing away from the wall, in front of one of the loudspeakers. What is the closest distance from the wall the person can stand and hear constructive interference? The speed of sound in air is 343 m/s.
A) 0.344 m
B) 0.729 m
C) 1.15 m
D) 1.64 m

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Multiple Choice

Q 87Q 87

Two in-phase loudspeakers are placed along a wall and are separated by a distance of 4.00 m. They emit sound with a frequency of 514 Hz. A person is standing away from the wall, in front of one of the loudspeakers. What is the closest distance from the wall the person can stand and hear destructive interference? The speed of sound in air is 343 m/s.
A) 0.344 m
B) 0.365 m
C) 0.729 m
D) 1.15 m
E) 1.64 m

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Multiple Choice

Q 88Q 88

Two in-phase loudspeakers that emit sound with the same frequency are placed along a wall and are separated by a distance of 5.00 m. A person is standing 12.0 m away from the wall, equidistant from the loudspeakers. When the person moves 1.00 m parallel to the wall, she experiences destructive interference for the first time. What is the frequency of the sound? The speed of sound in air is 343 m/s.
A) 211 Hz
B) 256 Hz
C) 422 Hz
D) 512 Hz
E) 674 Hz

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Multiple Choice

Q 89Q 89

Two in-phase loudspeakers that emit sound with the same frequency are placed along a wall and are separated by a distance of 8.00 m. A person is standing 12.0 m away from the wall, equidistant from the loudspeakers. When the person moves 3.00 m parallel to the wall, she experiences destructive interference for the second time. What is the frequency of the sound? The speed of sound in air is 343 m/s.
A) 278 Hz
B) 422 Hz
C) 452 Hz
D) 562 Hz
E) 694 Hz

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Multiple Choice

Q 90Q 90

An organ pipe, open at both ends, is 5.20 m long. What is its fundamental frequency? The speed of sound in air is 343 m/s.
A) 16.5 Hz
B) 33.0 Hz
C) 66.0 Hz
D) 99.0 Hz
E) 132 Hz

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Multiple Choice

Q 91Q 91

A 25.0-g string is stretched with a tension of 43.0 N between two fixed points 12.0 m apart. What is the frequency of the second harmonic?
A) 6.00 Hz
B) 12.0 Hz
C) 18.0 Hz
D) 24.0 Hz
E) 36.0 Hz

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Multiple Choice

Q 92Q 92

One of the harmonics of a string fixed at both ends has a frequency of 52.2 Hz and the next higher harmonic has a frequency of 60.9 Hz. What is the fundamental frequency of the string?
A) 26.1 Hz
B) 8.7 Hz
C) 4.35 Hz
D) 30.4 Hz
E) 17.4 Hz

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Multiple Choice

Q 93Q 93

One of the harmonics of a column of air open at one end and closed at the other has a frequency of 448 Hz and the next higher harmonic has a frequency of 576 Hz. What is the fundamental frequency of the air column?
A) 32 Hz
B) 64 Hz
C) 88 Hz
D) 128 Hz
E) 256 Hz

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Multiple Choice

Q 94Q 94

One of the harmonics of a column of air open at both ends has a frequency of 448 Hz and the next higher harmonic has a frequency of 576 Hz. What is the fundamental frequency of the air column?
A) 32 Hz
B) 64 Hz
C) 88 Hz
D) 128 Hz
E) 256 Hz

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Multiple Choice

Q 95Q 95

The lowest tone to resonate in an open pipe of length L is 200 Hz. Which one of the following frequencies will not resonate in the same pipe?
A) 200 Hz
B) 400 Hz
C) 600 Hz
D) 800 Hz
E) 900 Hz

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Multiple Choice

Q 96Q 96

The lowest tone to resonate in a closed pipe of length L is 200 Hz. Which of the following frequencies will not resonate in that pipe?
A) 200 Hz
B) 400 Hz
C) 600 Hz
D) 1000 Hz
E) 1400 Hz

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Multiple Choice

Q 97Q 97

One of the harmonics of a column of air open at one end and closed at the other has a frequency of 448 Hz and the next higher harmonic has a frequency of 576 Hz. How long is the air column? The speed of sound in air is 343 m/s.
A) 1.34 m
B) 0.670 m
C) 0.335 m
D) 1.00 m
E) 2.68 m

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Multiple Choice

Q 98Q 98

Two tuning forks have frequencies of 440 and 522 Hz. What is the beat frequency if both are sounding simultaneously?
A) 962 Hz
B) 431 Hz
C) 82 Hz
D) 55 Hz
E) 41 Hz

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Multiple Choice

Q 99Q 99

Two soldiers are marching side by side with a speed of 1.9 m/s, but one of them moves 92 cm for each step he takes, while the other moves only 84 cm. How often are they in step?
A) every 3.2 s
B) every 8.7 s
C) every 4.6 s
D) every 5.1 s
E) every 10 s

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Multiple Choice

Q 100Q 100

Two in-phase loudspeakers are some distance apart. They emit sound with a frequency of 536 Hz. A microphone is moved between the speakers along the line joining the two speakers with a constant speed of 1.60 m/s. What beat frequency is observed? The speed of sound in air is 343 m/s.
A) 5.00 Hz
B) 6.00 Hz
C) 7.00 Hz
D) 8.00 Hz
E) 9.00 Hz

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Multiple Choice

Q 101Q 101

Two strings of identical mass per unit length are stretched with the same tension with their ends fixed, but one string is 0.33 cm longer than the other. Waves on these strings propagate at 34.0 m/s. The fundamental frequency of the shorter string is 258 Hz. What is the beat frequency when each string is vibrating at its fundamental frequency?
A) 12.3 Hz
B) 9.00 Hz
C) 12.0 Hz
D) 12.7 Hz
E) 11.3 Hz

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Multiple Choice

Q 102Q 102

Two strings of identical mass and length are stretched with their ends fixed, but the tension in one string is 1.10 times greater than in the other. Waves on the string with the lower tension propagate at 35.2 m/s. The fundamental frequency of that string is 258 Hz. What is the beat frequency when each string is vibrating at its fundamental frequency?
A) 11.0 Hz
B) 9.00 Hz
C) 13.7 Hz
D) 12.6 Hz
E) 17.1 Hz

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Multiple Choice

Q 103Q 103

A bat emits a sound at a frequency of 39.0 kHz as it approaches a wall. The bat detects beats with a frequency of 827 Hz between the sound it emits and the echo bouncing from the wall. What is the speed of the bat? The speed of sound in air is 343 m/s.
A) 2.7 m/s
B) 3.0 m/s
C) 3.6 m/s
D) 5.4 m/s
E) 9.0 m/s

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Multiple Choice

Q 104Q 104

A policeman in a stationary car measures the speed of approaching cars by means of an ultrasonic device that emits a sound with a frequency of 39.6 kHz. A car is approaching him at a speed of 35.0 m/s. The wave is reflected by the car and interferes with the emitted sound producing beats. What is the frequency of the beats? The speed of sound in air is 343 m/s.
A) 5000 Hz
B) 4500 Hz
C) 8490 Hz
D) 9000 Hz
E) 4250 Hz

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Multiple Choice