# Quiz 15: Wave Motion

Physics & Astronomy

Q 1Q 1

Which of the following statements is true?
A) Waves transmit energy but not momentum.
B) Waves transmit momentum but not energy.
C) Waves transmit both energy and momentum.
D) Waves transmit neither energy nor momentum.
E) Waves can transmit either energy or momentum but not both.

Free

Multiple Choice

C

Q 2Q 2

During the passage of a longitudinal wave, a particle of the medium
A) remains in a fixed position.
B) moves in a circle.
C) moves at right angles to the direction of propagation.
D) moves forward and backward along the line of propagation.
E) moves forward with the velocity of the wave.

Free

Multiple Choice

D

Q 3Q 3

A longitudinal wave is distinguished from a transverse wave by the fact that in longitudinal waves
A) the particle vibration is parallel to the direction of propagation.
B) the particle vibration is perpendicular to the direction of propagation.
C) energy is transported from one point in space to another point.
D) vibrations occur only in air or water.
E) energy is not transported from one point in space to another point.

Free

Multiple Choice

A

Q 4Q 4

Which of the following statements about longitudinal and transverse pressure waves is NOT true?
A) Longitudinal pressure waves can travel through fluids.
B) Transverse pressure waves can travel through fluids.
C) Longitudinal pressure waves can travel through solids.
D) Transverse pressure waves can travel through solids.
E) Both longitudinal and transverse pressure waves transport energy.

Free

Multiple Choice

Q 5Q 5

Both particles and waves transfer energy from one location to another. Which of the following statements is true?
A) Both methods of energy transfer follow the conservation of energy principle.
B) Energy transfer by particles follows the conservation of energy principle but waves do not.
C) Energy transfer by waves follows the conservation of energy principle but particles do not.
D) Whether the transfer of energy by a wave follows the conservation of energy principle depends on the speed of the wave.
E) Whether the transfer of energy by a particle follows the conservation of energy principle depends on the speed of the particle.

Free

Multiple Choice

Q 6Q 6

A particle is subject to a wave motion. Its distance from the equilibrium position at any particular time is called its
A) amplitude
B) displacement
C) phase
D) wavelength
E) period

Free

Multiple Choice

Q 7Q 7

In which of the following is the speed of sound greatest?
A) air
B) water
C) a vacuum
D) wood
E) steel

Free

Multiple Choice

Q 8Q 8

A string under tension carries transverse waves traveling at speed v. If the same string is under four times the tension, what is the wave speed?
A) v
B) 2v
C) v/2
D) 4v
E) v/4

Free

Multiple Choice

Q 9Q 9

A string under tension carries a transverse wave traveling at speed v. If the tension in the string is halved, what is the wave speed?
A) The wave speed is unchanged.
B) The wave speed is halved.
C) The wave speed is quadrupled.
D) The wave speed decreases to about 71% of v.
E) The wave speed increases by about 41%.

Free

Multiple Choice

Q 10Q 10

A string under tension carries a transverse wave traveling at speed v. If the linear density of the string is halved, what is the wave speed?
A) The wave speed is unchanged.
B) The wave speed is halved.
C) The wave speed is quadrupled.
D) The wave speed decreases to about 71% of v.
E) The wave speed increases by about 41%.

Free

Multiple Choice

Q 11Q 11

A string under tension carries a transverse wave traveling at speed v. If the linear density of the string is doubled, what is the wave speed?
A) The wave speed is unchanged.
B) The wave speed is halved.
C) The wave speed is quadrupled.
D) The wave speed decreases to about 71% of v.
E) The wave speed increases by about 41%.

Free

Multiple Choice

Q 12Q 12

A string under tension carries a transverse wave traveling at speed v. If the tension in the string is quadrupled and the linear density of the string is doubled, what is the wave speed?
A) The wave speed is unchanged.
B) The wave speed is halved.
C) The wave speed is quadrupled.
D) The wave speed decreases to about 71% of v.
E) The wave speed increases by about 41%.

Free

Multiple Choice

Q 13Q 13

A string under tension carries a transverse wave traveling at speed v. If the tension in the string is halved and the linear density of the string is quadrupled, what is the wave speed?
A) The wave speed is unchanged.
B) The wave speed is halved.
C) The wave speed is quadrupled.
D) The wave speed decreases to about 71% of v.
E) The wave speed increases by about 41%.

Free

Multiple Choice

Q 14Q 14

A piano wire has a tension of 650 N and a mass per unit length of 0.060 g/cm. What is the speed of waves on this wire?
A) 1.0 10

^{2}m/s B) 3.3 10^{2}m/s C) 1.0 10^{3}m/s D) 33 m/s E) 52 m/sFree

Multiple Choice

Q 15Q 15

A general rule for estimating the distance in kilometers between you and a lightning bolt is to count the number of seconds between the time you see the flash and the time you hear the thunder and then divide by
A) 2
B) 3
C) 4
D) 5
E) None of these is correct.

Free

Multiple Choice

Q 16Q 16

Sound travels at 340 m/s in air and 1500 m/s in water. A sound of 256 Hz is made under water. In the air,
A) the frequency remains the same but the wavelength is shorter.
B) the frequency is higher but the wavelength stays the same.
C) the frequency is lower but the wavelength is longer.
D) the frequency is lower and the wavelength is shorter.
E) both the frequency and the wavelength remain the same.

Free

Multiple Choice

Q 17Q 17

Which curve best illustrates the variation of wave velocity with tension in a vibrating string?
A) 1
B) 2
C) 3
D) 4
E) 5

Free

Multiple Choice

Q 18Q 18

Which curve best illustrates the variation of wave velocity with linear density in a vibrating string?
A) 1
B) 2
C) 3
D) 4
E) 5

Free

Multiple Choice

Q 19Q 19

Which curve best represents the variation of wave velocity with linear density in a vibrating string?
A) 1
B) 2
C) 3
D) 4
E) 5

Free

Multiple Choice

Q 20Q 20

Which curve best represents the variation of wave velocity with tension in a vibrating string?
A) 1
B) 2
C) 3
D) 4
E) 5

Free

Multiple Choice

Q 21Q 21

A string exactly two meters long has a mass of 10.0 g and is under a tension of 12.5 N. The speed of a transverse wave in this string is
A) 1.58 m/s
B) 15.8 m/s
C) 25.0 m/s
D) 44.7 m/s
E) 50.0 m/s

Free

Multiple Choice

Q 22Q 22

A string is stretched by a force of 4.0 N. The mass per unit length of the string is 4.0 10

^{-4}kg/m. A transverse wave would travel along this string with a velocity of approximately A) 0.80 cm/s B) 2.0 cm/s C) 8.0 cm/s D) 50 m/s E) 1.0 10^{2}m/sFree

Multiple Choice

Q 23Q 23

A string of mass 2.4 10

^{-3}kg and length 0.60 m vibrates transversely in such a way that its fundamental frequency is 100 Hz. The tension on this string must be approximately A) 0.16 N B) 0.32 N C) 13 N D) 26 N E) 58 NFree

Multiple Choice

Q 24Q 24

The speed of sound in air at 0ºC is 331 m/s. What is the speed of sound in air at -40ºC?
A) 241 m/s
B) 282 m/s
C) 306 m/s
D) 309 m/s
E) 379 m/s

Free

Multiple Choice

Q 25Q 25

The curve that represents the speed of sound in a gas plotted against the kelvin temperature is
A) 1
B) 2
C) 3
D) 4
E) 5

Free

Multiple Choice

Q 26Q 26

Increasing the temperature, expressed in kelvins, in a gas by 125% will produce an increase in the speed of sound in the gas of approximately
A) 25%
B) 18%
C) 12%
D) 9%
E) 4%

Free

Multiple Choice

Q 27Q 27

The speed of sound in dry air at 20ºC is 343 m/s. The speed of sound in dry air at 80ºC is
A) 86.0 m/s
B) 172 m/s
C) 377 m/s
D) 686 m/s
E) 1.27 km/s

Free

Multiple Choice

Q 28Q 28

When the frequency of a source is doubled, the sound produced
A) travels at half its former speed.
B) travels at twice its former speed.
C) has half its former wavelength.
D) has twice its former wavelength.
E) is greatly improved in quality.

Free

Multiple Choice

Q 29Q 29

If the speed of sound is 331 m/s at 0C and at temperature T it is 350 m/s, find T.
A) 1C
B) 16C
C) 32C
D) 16C
E) none of the above

Free

Multiple Choice

Q 30Q 30

A stationary ship generates a sound signal at the bow and has a receiver system at the stern of the ship 100 m away. The difference in time between the signal arriving at the stern traveling directly through the air and the signal reflected from the sea bottom is 0.5 second. If the velocity of sound in air is 331 m/s and in water is 1435 m/s, calculate the depth of water below the ship.
A) 1150 m
B) 574 m
C) 359 m
D) 396 m
E) 450 m

Free

Multiple Choice

Q 31Q 31

A stationary ship generates a sound signal at the bow and has a receiver system at the stern of the ship 100 m away. The signal arriving at the stern traveling directly through the air and the signal reflected from the sea bottom arrive at the sensor at the same time. If the velocity of sound in air is 331 m/s and in water is 1435 m/s, calculate the depth of water below the ship.
A) 434 m
B) 422 m
C) 217 m
D) 211 m
E) 192 m

Free

Multiple Choice

Q 32Q 32

A sound pulsar unit puts out short sound bursts at constant time intervals. This unit also has a receiver to listen to the time delay from an echo from any objects or walls. If the unit is positioned such that the echo time corresponds to the sound burst interval of 0.6 s, find the distance to the reflecting wall. (velocity of sound in air = 331 m/s)
A) 150 m
B) 50.0 m
C) 200 m
D) 100 m
E) none of the above

Free

Multiple Choice

Q 33Q 33

Which of the following function is NOT a possible wave equation? A and c are constants. The other symbols have their usual meaning.
A) y(x,t) = 1/(x - vt)
B) y(x,t) = A e

^{-vxt/c }C) D) y(x,t) = A cos (kx) sin (ωt) E) y(x,t) = A sin(kx + ωt)Free

Multiple Choice

Q 34Q 34

In a seismic event, two types of waves are created, a P-wave (longitudinal) and an S-wave (transverse). The waves travel at speeds of 8 km/s and 5 km/s respectively. At a monitoring station, a P-wave is observed 10 s before the S-wave. How far is the seismic activity from the station? Assume that the waves travel in a straight line.
A) 50 km
B) 80 km
C) 30 km
D) 133 km
E) none of the above

Free

Multiple Choice

Q 35Q 35

Geologists use explosives to map the subterranean. The times for the reflected waves to arrive at a monitoring station can tell a great deal about the composition of the rock structures. Suppose the time it takes for a wave that is reflected from the interface of (1) and (2) is 2 s, and the time for another wave that is reflected between (2) and (3) is 2.5 s and the speed of the wave in layer (1) is 6 km/s and in layer (2) is 4 km/s, how thick is layer (2)?
A) 2 km
B) 1 km
C) 3 km
D) 6 km
E) 8 km

Free

Multiple Choice

Q 36Q 36

Use the following scenario to answer the next questions. A rope of length L and linear mass density is tied to the ceiling on one end. The other end is tied to a spring with spring constant k, and the spring is then attached to the floor, extending it by A.
-The tension of the rope at height y from the spring is
A) kA
B) gy
C) gy + kA
D) gy kA
E) kA gy

Free

Multiple Choice

Q 37Q 37

Use the following scenario to answer the next questions. A rope of length L and linear mass density is tied to the ceiling on one end. The other end is tied to a spring with spring constant k, and the spring is then attached to the floor, extending it by A.
-The speed of a wave pulse at height h from the spring is
A)
B)
C)
D)
E)

Free

Multiple Choice

Q 38Q 38

Use the following scenario to answer the next questions. A rope of length L and linear mass density is tied to the ceiling on one end. The other end is tied to a spring with spring constant k, and the spring is then attached to the floor, extending it by A.
-The time it takes for a wave pulse to travel from the bottom of the rope to the ceiling is
A)
B)
C)
D)
E)

Free

Multiple Choice

Q 39Q 39

A triangular wave pulse as shown by the blue line can be formed by adding
A) harmonic sine waves with different frequencies and intensities.
B) harmonic cosine waves with different frequencies and intensities.
C) a combination of harmonic sine and cosine waves with different frequencies and intensities.
D) either (A), (B) or (C)
E) it is not possible to form triangular using harmonic waves.

Free

Multiple Choice

Q 40Q 40

A wave is traveling with a speed v along the x axis in the positive direction. The upper graph shows the displacement y versus the distance x for a given instant of time. The lower graph shows the displacement y versus the time t for any given point x. From the information in the graphs, what is the wave speed v?
A) 8.0 m/s
B) 4.0 m/s
C) 6.0 m/s
D) There is not enough information to solve the problem.
E) None of these is correct.

Free

Multiple Choice

Q 41Q 41

A traveling wave passes a point of observation. At this point, the time between successive crests is 0.2 s. Which of the following statements can be justified?
A) The wavelength is 5 m.
B) The frequency is 5 Hz.
C) The velocity of propagation is 5 m/s.
D) The wavelength is 0.2 m.
E) There is not enough information to justify any of these statements.

Free

Multiple Choice

Q 42Q 42

A set of waves has a speed of 4.2 m/s and a frequency of 2.0 Hz. The wavelength is
A) 8.4 m
B) 2.1 m
C) 0.48 m
D) 0.84 m
E) 3.2 m

Free

Multiple Choice

Q 43Q 43

Waves on the surface of a liquid are observed to have a wavelength of 12.9 mm and a speed of 30.9 cm/s. The frequency of the wave motion is
A) 1.8 mHz
B) 24 Hz
C) 42 mHz
D) 2.4 Hz
E) 2.4 mHz

Free

Multiple Choice

Q 44Q 44

As a wave moves to the right in an elastic rope, a sequence of pictures (1 through 6) is taken at intervals of one second. An arrow points out a particle that is attached to the rope. If the width of the picture is 8 cm, this wave has a period of
A) 0.2 s
B) 10 s
C) 3 s
D) 6 s
E) 12 s

Free

Multiple Choice

Q 45Q 45

In a sinusoidal traveling wave, the distance between two points that differ in phase by 2 radians is the
A) frequency.
B) period.
C) amplitude.
D) phase constant.
E) wavelength.

Free

Multiple Choice

Q 46Q 46

The graph shows a wave moving from left to right. If the period of this wave motion is 50 ms, the wave is moving with a velocity of
A) 40 cm/s
B) 1.6 m/s
C) 1.6 m/s
D) 80 cm/s
E) 0.40 cm/s

Free

Multiple Choice

Q 47Q 47

The equation of a traveling wave is
Y(x, t) = 0.02 cos(0.25x - 500t)
Where the units are SI. The velocity of the wave is
A) 4.0 m/s
B) 10 m/s
C) 0.13 km/s
D) 0.50 km/s
E) 2.0 km/s

Free

Multiple Choice

Q 48Q 48

The equation of a transverse wave is
Y(x, t) = 0.02 cos(10x - 400t)
Where the units are SI. The velocity of the wave is
A) 0.20 m/s
B) 8 m/s
C) 40 m/s
D) 0.20 km/s
E) 0.40 km/s

Free

Multiple Choice

Q 49Q 49

The graph shows a wave of frequency 3.0 Hz traveling to the right. The phase velocity of this wave is
A) 6 m/s
B) 13 m/s
C) 60 m/s
D) 90 m/s
E) 0.12 km/s

Free

Multiple Choice

Q 50Q 50

A sinusoidal wave train is moving along a string. The equation giving the displacement y of a point at coordinate x has the form
Y(x, t) = 0.15 sin[10(t - x/60)]
Where the units are SI. The wavelength is
A) 8.0 cm
B) 15 cm
C) 6.0 m
D) 12 m
E) 60 m

Free

Multiple Choice

Q 51Q 51

The graph shows a wave traveling to the right with a velocity of 4 m/s. The equation that best represents the wave is
A) y(x, t) = 2 sin(x/4 - t) m
B) y(x, t) = 2 sin(16x - 8t) m
C) y(x, t) = 2 sin(x/4 + t) m
D) y(x, t) = 4 sin(x/4 - t) m
E) y(x, t) = 4 sin(16x - 8t) m

Free

Multiple Choice

Q 52Q 52

A wave moving in the positive x direction has an amplitude of 0.4 m, a frequency of 0.25 Hz, and a wavelength of 24 m. An equation, in which the units are SI, that might describe this wave is
A) y(x, t) = 0.2 sin 2(t/4 + x/24)
B) y(x, t) = 0.4 sin 2(t/4 - x/24)
C) y(x, t) = 0.4 sin 8(t - x/6)
D) y(x, t) = 0.2 sin 0.5(t/4 - x/24)
E) y(x, t) = 0.4 sin 2(t/4 + x/6)

Free

Multiple Choice

Q 53Q 53

The particle displacement in a simple harmonic wave is given by y(x, t) = 2 sin 4(t + x/8),
Where the units are SI. A graph of particle displacement as a function of position at
T = 0.5s would include points
A) A and D
B) B and D
C) C and E
D) B and E
E) D and F

Free

Multiple Choice

Q 54Q 54

The equation that gives the particle displacement of a medium in which there is a simple harmonic progressive wave is
Y(x, t) = (2/) sin (x - 4t),
Where the units are SI. At t = 2 s, the velocity of a particle at x = 10 m is
A) 0
B) 2 m/s
C) 4/ m/s
D) 4 m/s
E) 8 m/s

Free

Multiple Choice

Q 55Q 55

An equation that gives the particle displacement for a medium in which there is a simple harmonic traveling wave is
Y(x, t) = (2/) sin (3x + 2t),
Where x and y are in centimeters and t is in seconds. At t = 2 s the speed of a particle at the location x = 4 cm is
A) 0
B) 2 cm/s
C) 4 cm/s
D) 6 cm/s
E) 8 cm/s

Free

Multiple Choice

Q 56Q 56

A sinusoidal wave train is moving along a string. The equation giving the displacement as a function of position and time is
Y(x, t) = 0.12 sin 8(t - x/50),
Where the units are SI. For a particle at x = 5 m when t = 2.4 s, the velocity of the particle is
A) 3.7 cm/s
B) 27 cm/s
C) 93 cm/s
D) 1.6 m/s
E) 3.0 m/s

Free

Multiple Choice

Q 57Q 57

The power transmitted by any harmonic wave varies directly as
A) the period.
B) the square root of the frequency.
C) the amplitude.
D) the amplitude squared.
E) None of these is correct.

Free

Multiple Choice

Q 58Q 58

Two waveforms of the same frequency are moving to the right. The power P

_{A}transmitted by wave A is equal to A) 2P_{B}/3 B) 9P_{B}/4 C) P_{B }_{ }_{ }D) 4P_{B}/9 E) P_{B }Free

Multiple Choice

Q 59Q 59

The average rate at which energy is transmitted along a string depends on
A) the linear density of the string.
B) the square of the angular frequency of the source.
C) the square of the amplitude of the wave.
D) the speed of the wave.
E) all of these factors

Free

Multiple Choice

Q 60Q 60

To double the rate at which energy is transmitted along a string, you could
A) double the angular frequency of the source.
B) double the amplitude of the wave.
C) double the tension in the string.
D) quadruple the tension in the string.
E) halve the linear density of the string.

Free

Multiple Choice

Q 61Q 61

Electromagnetic waves
A) include light, radio waves, X rays, gamma rays, and microwaves.
B) do not require a medium for propagation.
C) travel through a vacuum with a speed of approximately 3 10

^{8}m/s. D) are produced when free electrons accelerate. E) are described by all of the aboveFree

Multiple Choice

Q 62Q 62

If you were to double the amplitude of a wave on a string while keeping the speed and frequency of the wave constant, the energy delivered by the wave would
A) double.
B) quadruple.
C) be reduced 50%.
D) be reduced to 25% of its previous value.
E) be unchanged.

Free

Multiple Choice

Q 63Q 63

If you were to reduce the amplitude of a wave on a string by half while keeping the speed and frequency of the wave constant, the energy delivered by the wave would
A) double.
B) quadruple.
C) be reduced 50%.
D) be reduced to 25% of its previous value.
E) be unchanged.

Free

Multiple Choice

Q 64Q 64

If you were to double the frequency of a wave on a string while keeping the speed and amplitude of the wave constant, the energy delivered by the wave would
A) double.
B) quadruple.
C) be reduced 50%.
D) be reduced to 25% of its previous value.
E) be unchanged.

Free

Multiple Choice

Q 65Q 65

If you were to reduce the frequency of a wave on a string by a factor of 2 while keeping the speed and amplitude of the wave constant, the rate at which energy is delivered by the wave would
A) double.
B) quadruple.
C) be reduced 50%.
D) be reduced to 25% of its previous value.
E) be unchanged.

Free

Multiple Choice

Q 66Q 66

If you were to double the speed of a wave on a string while keeping the frequency and amplitude of the wave constant, the rate at which energy is delivered by the wave would
A) double.
B) quadruple.
C) be reduced 50%.
D) be reduced to 25% of its previous value.
E) be unchanged.

Free

Multiple Choice

Q 67Q 67

If you were to quadruple the speed of a wave on a string while keeping the frequency and amplitude of the wave constant, the rate at which energy is delivered by the wave would
A) double.
B) quadruple.
C) be reduced 50%.
D) be reduced to 25% of its previous value.
E) be unchanged.

Free

Multiple Choice

Q 68Q 68

If you were to double the amplitude and halve the frequency of a wave on a string while keeping the amplitude of the wave constant, the rate at which energy is delivered by the wave would
A) double.
B) quadruple.
C) be reduced 50%.
D) be reduced to 25% of its previous value.
E) be unchanged.

Free

Multiple Choice

Q 69Q 69

The human ear can be sensitive to sound frequencies up to 20 kHz. What wavelength does this correspond to at normal temperature and pressure?
A) 0.165 m
B) 165 cm
C) 16.5 mm
D) 1650 10

^{}^{4}m E) 1.65 mmFree

Multiple Choice

Q 70Q 70

Waves of amplitude 1.1 cm and wavelength 40 cm move along a 12-m long string that has a mass of 70 g and is under a tension of 15 N. Calculate the velocity of the wave.
A) 51 m/s
B) 2570 m/s
C) 16 m/s
D) 15 m/s
E) 331 m/s

Free

Multiple Choice

Q 71Q 71

Waves of amplitude 1.3 cm move along a 14-m long string that has a mass of 90 g and is under a tension of 18 N. If the average total energy of the waves in the string is 5 J, calculate the frequency of the waves.
A) 21 Hz
B) 811 Hz
C) 129 Hz
D) 92 Hz
E) 256 Hz

Free

Multiple Choice

Q 72Q 72

A wave of frequency f is transmitted on a string with tension T. If the tension is increased by a factor of 4 and the frequency and amplitude are unchanged, the power transmitted changed by
A) 1/2
B) 1/4
C) 2
D) 4
E) 1

Free

Multiple Choice

Q 73Q 73

You have a rope that is 10 m long and has a mass of 0.2 kg. In addition, you have an oscillator that can generate a 5 Hz wave with an amplitude of 10 cm. What should the tension in the rope be if you need to transmit 10 W of power along the rope?
A) 102 N
B) 205 N
C) 320 N
D) 51 N
E) 250 N

Free

Multiple Choice

Q 74Q 74

The intensity of a certain spherical wave is 8.0 W/m

^{2}at a distance of 1.0 m from the source. If the medium is isotropic and nonabsorbing, the intensity 100 m from the source is A) 8.0 W/m^{2 }B) 6.4 10^{-4}W/m^{2 }C) 1.9 10^{-4}W/m^{2 }D) 8.0 10^{-4}W/m^{2 }E) 1.9 10^{-6}W/m^{2 }Free

Multiple Choice

Q 75Q 75

The intensity of a wave at a certain point is I. A second wave has twice the energy density and three times the speed of the first. What is the intensity of the second wave?
A) I
B) 2I
C) 3I
D) 6I
E) 2I/3

Free

Multiple Choice

Q 76Q 76

The sound level of a dog's bark is 50 dB. The intensity of a rock concert is 10,000 times that of the dog's bark. What is the sound level of the rock concert?
A) 10,050 dB
B) 500,000 dB
C) 90 dB
D) 2000 dB
E) 54 dB

Free

Multiple Choice

Q 77Q 77

A musical pitch is played at 60 dB. Another is played that sounds four times as loud. The sound intensity level of the second pitch is
A) 80 dB
B) 100 dB
C) 66 dB
D) 64 dB
E) 240 dB

Free

Multiple Choice

Q 78Q 78

Two sounds differ by 30 dB. The intensity of the louder sound I

_{L}, compared with the softer I_{S}, is I_{L}/I_{S}. The value of the ratio is A) 1000 B) 30 C) 9 D) 100 E) 300Free

Multiple Choice

Q 79Q 79

Two sounds differ by 20 dB. This means that the louder sound is _____ times as intense and _____ times as loud.
A) twenty; twenty
B) one hundred; twenty
C) twenty; four
D) one hundred; four
E) two; two

Free

Multiple Choice

Q 80Q 80

If a sound of intensity I = 1.0 10

^{-6}W/m^{2}falls on a detector of area A = 7.0 10^{-5}m^{2}(about the size of your eardrum), how much power is received by the detector? A) 6.2 10^{-14}W B) 1.0 10^{-6}W C) 7.0 10^{-11}W D) 1.4 10^{-2}W E) 70 WFree

Multiple Choice

Q 81Q 81

At an outdoor bandstand, what would be the difference in the sound intensity level (dB) received by a listener 5 m from the bandstand and a listener 40 m from the bandstand, assuming there is no sound reflection? [ = 10 log(I/I

_{0})] A) 8 dB B) 9 dB C) 10 dB D) 18 dB E) The answer depends on how loudly the band plays.Free

Multiple Choice

Q 82Q 82

A noisy workplace has a noise level of 90 dB. You want to reduce this to a more comfortable 75 dB. By what factor must the power of the noise source be reduced? (That is, what is the ratio of the new power to the old?)
A) 0.83
B) 0.67
C) 0.32
D) 0.032
E) 0.010

Free

Multiple Choice

Q 83Q 83

Workmen are digging up the road using pneumatic tools. If a single tool creates a noise level of 88 decibels a few meters away, calculate the noise level if four such tools were in operation the same distance away.
A) 176 dB
B) 90 dB
C) 352 dB
D) 94 dB
E) 92 dB

Free

Multiple Choice

Q 84Q 84

The sound intensity in front of a loudspeaker diaphragm vibrating at 2 kHz is 4.3 W/m

^{2}, with an acoustic power output of 0.3 W. Calculate the diameter of the diaphragm. A) 3 cm B) 9 cm C) 15 cm D) 30 cm E) 60 cmFree

Multiple Choice

Q 85Q 85

You are in a park when you spot your friend 100 m away. At what lowest decibel should you shout your greetings so that your friend can just hear you? Assume that your friend has normal hearing.
A) 30 dB
B) 40 dB
C) 50 dB
D) 60dB
E) 70 dB

Free

Multiple Choice

Q 86Q 86

We can hear sounds that are produced around a corner but cannot see light that is produced around a corner because
A) light travels only in straight lines whereas sound can travel in a curved path.
B) sound has more energy than light.
C) sound has shorter wavelengths than light.
D) sound has longer wavelengths than light.
E) None of these is correct.

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Multiple Choice

Q 87Q 87

A cord stretched to a tension F

_{T}, consists of two sections whose linear densities are μ_{1}and μ_{2 }(< _{1}). A wave of frequency f and speed v is sent along the cord from one end. Which of the following statements is true about the transmitted and reflected waves? A) Both the transmitted and reflected waves have the same speed, v. B) Both the transmitted and reflected waves have the same frequency, f. C) Both the transmitted and reflected waves have the same wavelength, = v/f. D) The reflected wave is inverted compared to the transmitted wave. E) none of the aboveFree

Multiple Choice

Q 88Q 88

A wave given with amplitude A = 10 cm travels along a cord which has two sections, one with linear density 0.1 kg/m and the other with linear density 0.2 kg/m. The wave travels along the cord from the lighter density to the heavier. If the tension in the cord is 50 N, the amplitude of the reflected wave is
A) 0.65 cm
B) 1.5 cm
C) 5.9 cm
D) 7.4 cm
E) 8.3 cm

Free

Multiple Choice

Q 89Q 89

When a dense fog blanket an area at night, you can often hear traffic noises coming from a distance highway or jets taking off from an airport several miles away. The reason is because
A) when it is foggy there are layers of air at different temperatures so that some sound waves are reflected at the interface rather than spreading in all directions.
B) when it is foggy, the air is still so you can hear sound better.
C) on foggy days or nights your hearing is more acute, to make up for the reduced visibility.
D) it is all in your head, it just seems that way.
E) none of the above

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Multiple Choice

Q 90Q 90

A pulse moves in a string toward a free end (a ring on a post) as indicated in the sketch. On reflection, the pulse would most nearly be represented by
A) 1
B) 2
C) 3
D) 4
E) 5

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Multiple Choice

Q 91Q 91

The pulse shown is moving in the string toward a fixed end at the wall. After reflection at the wall, which figure correctly represents the pulse?
A) 1
B) 2
C) 3
D) 4
E) 5

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Multiple Choice

Q 92Q 92

From the figure above, you can conclude that
A) the medium to the left of the boundary is denser than the medium to the right.
B) the medium to the right of the boundary is denser than the medium to the left.
C) the pulse is initially traveling from right to left.
D) the wave has lost energy as a result.
E) None of these is correct.

Free

Multiple Choice

Q 93Q 93

From the figure above, you can conclude that
A) the medium to the left of the boundary is denser than the medium to the right.
B) the medium to the right of the boundary is denser than the medium to the left.
C) the pulse is initially traveling from right to left.
D) the wave has lost energy as a result.
E) None of these is correct.

Free

Multiple Choice

Q 94Q 94

From the figure, you can conclude that
A) the wave travels slower in the medium to the left of the interface than in the medium to the right of the interface.
B) the wave travels faster in the medium to the left of the interface than in the medium to the right of the interface.
C) the wave is traveling with the same speed on both sides of the interface.
D) the angle of incidence is equal to the angle of refraction.
E) total internal reflection is not possible for a wave traveling from left to right.

Free

Multiple Choice

Q 95Q 95

The extent to which waves diffract when they encounter an obstacle or aperture depends on
A) the size of the aperture or obstacle.
B) the wavelength of the waves.
C) whether the wavelength is small or large relative to the size of the obstacle or aperture.
D) the speed of the waves.
E) None of these is correct.

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Multiple Choice

Q 96Q 96

While you are standing on a corner, a police car with a 1-kHz siren drives past you at
30 m/s with its siren on. The speed of sound is 340 m/s. After the car has passed, the frequency you hear is about
A) 1.10 kHz
B) 1.09 kHz
C) 1.00 kHz
D) 919 Hz
E) 912 Hz

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Multiple Choice

Q 97Q 97

A train traveling at 90 km/h is blowing its whistle at 440 Hz as it crosses a level crossing. You are waiting at the crossing and hear the pitch of the whistle change as the train passes you. The sound you hear changes from a frequency of _____ to a frequency of _____. (Take the speed of sound to be 340 m/s.)
A) 475 Hz; 410 Hz
B) 410 Hz; 475 Hz
C) 408 Hz; 472 Hz
D) 472 Hz; 408 Hz
E) 598 Hz; 348 Hz

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Multiple Choice

Q 98Q 98

A blue line in the spectrum of the hydrogen atom has a wavelength = 486 nm. In the hydrogen-atom spectrum emitted by a distant galaxy, this line is observed on Earth at = 550 nm. With what speed is this galaxy receding from us? (The speed of light is 3.0 10

^{8}m/s.) A) 1.31 10^{7}m/s B) 1.13 10^{8}m/s C) 2.65 10^{8}m/s D) 3.49 10^{7}m/s E) 3.95 10^{7}m/sFree

Multiple Choice

Q 99Q 99

Car A moves at speed v toward car B, which is at rest. The frequency of car A's horn is observed by car B to be f. What is the frequency of car A's horn as heard by an observer in car B if car A is at rest and car B moves at speed v toward car A (assume there is no wind)?
A) f
B) greater than f
C) less than f
D) either greater than or less than f
E) 2f

Free

Multiple Choice

Q 100Q 100

The frequency of a car horn is f. What frequency is observed if both the car and the observer are at rest, but a wind is blowing toward the observer?
A) f
B) greater than f
C) less than f
D) either greater or less than f
E) far greater than f, depending on how wind speed compares with the speed of sound

Free

Multiple Choice

Q 101Q 101

A siren of frequency 3.20 kHz moves away from a stationary observer with a speed of 30.5 m/s. If the speed of sound is 335 m/s, the frequency heard by the observer is
A) 2.66 kHz
B) 2.93 kHz
C) 3.49 kHz
D) 3.52 kHz
E) 3.84 kHz

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Multiple Choice

Q 102Q 102

A passenger car traveling due east at 53.6 m/s passes a truck traveling due east at
13)4 m/s. After the car passes, the horn on the truck is blown at a frequency of 350 Hz. The speed of sound in air is 335 m/s. The frequency heard by the driver of the car is
A) 290 Hz
B) 306 Hz
C) 314 Hz
D) 400 Hz
E) 434 Hz

Free

Multiple Choice

Q 103Q 103

A woman drives toward the face of a cliff at 26.8 m/s. She sounds a burst on her 500-Hz car horn and then listens for the echo. Assuming 313 m/s to be the speed of sound, the woman hears an echo frequency of
A) about 595 Hz
B) about 545 Hz
C) exactly 500 Hz
D) about 460 Hz
E) exactly 1000 Hz

Free

Multiple Choice

Q 104Q 104

A sound source of frequency f moves with constant velocity (less than the speed of sound) through a medium that is at rest. A stationary observer hears a sound whose frequency is appreciably different from f because
A) the equation that relates velocity of propagation, frequency, and wavelength of a sound traveling through a medium does not apply in this situation.
B) the sound wave travels through the medium with a velocity different from that which it would have if the source were at rest.
C) the frequency of the source is changed because of its motion.
D) the wavelength established in the medium is not the same as it would be if the source were at rest.
E) interference effects set up a standing-wave pattern that alters the frequency.

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Multiple Choice

Q 105Q 105

A speedboat moving at 20.6 m/s sounds a signal on its horn, producing a tone of 320 Hz. There is no wind, and the speed of sound in air is 329 m/s. The apparent frequency of the sound heard by an observer in another boat moving in the opposite direction and approaching the first at a speed of 15.4 m/s is
A) 282 Hz
B) 287 Hz
C) 316 Hz
D) 357 Hz
E) 369 Hz

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Multiple Choice

Q 106Q 106

The observed pitch alone makes it possible to judge whether a sound source is
A) passing by.
B) approaching or receding.
C) stationary or moving.
D) stationary while the observer moves or moving while the observer is stationary.
E) at a considerable distance or nearby.

Free

Multiple Choice

Q 107Q 107

A locomotive moving at a constant speed approaches and then passes a man standing at a crossing. The frequency of the locomotive's horn as the man hears it
A) gradually increases and then decreases.
B) gradually decreases and then increases.
C) abruptly changes as the locomotive passes.
D) does not change at all.
E) produces beats due to the Doppler effect.

Free

Multiple Choice

Q 108Q 108

A jet engine emits a whine of frequency 3000 Hz. When the engine is moving directly away from an observer at half the speed of sound, an observer hears a frequency of
A) 1000 Hz
B) 1500 Hz
C) 2000 Hz
D) 4500 Hz
E) 6000 Hz

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Multiple Choice

Q 109Q 109

The object shown in the figure is
A) traveling from 2 toward 4.
B) traveling from 3 toward 1.
C) traveling from 1 toward 3.
D) traveling from 4 toward 2.
E) not in motion.

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Multiple Choice

Q 110Q 110

The angle of the shock wave shown in this photograph is closest to
A) 10º
B) 20º
C) 40º
D) 80º
E) 90º

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Multiple Choice

Q 111Q 111

The angle of the shock wave produced by a jet traveling at Mach 2 at an altitude of
3000 m (assume the speed of sound to be 340 m/s at this altitude) is approximately
A) 30º
B) 40º
C) 50º
D) 60º
E) 80º

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Multiple Choice

Q 112Q 112

The angle of the shock wave produced by a jet traveling at Mach 3 at an altitude of
4000 m (assume the speed of sound to be 340 m/s at this altitude) is approximately
A) 10º
B) 13º
C) 19º
D) 20º
E) 38º

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Multiple Choice

Q 113Q 113

A police car siren emits a sound at 600 Hz. If observer A moves toward the source at
50 km/hr, and the police car is traveling toward observer A at 100 km/hr (all speeds relative to the road), calculate the siren frequency heard by the observer A (assume the speed of sound in air = 343 m/s).
A) 626 Hz
B) 600 Hz
C) 679 Hz
D) 577 Hz
E) 970 Hz

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Multiple Choice

Q 114Q 114

A police car siren emits a sound at 600 Hz. If an observer moves toward the source at
50 km/hr, and the police car approaches the observer at 100 km/hr (all speeds relative to the road), calculate the siren frequency heard by the driver of the police car (assume the speed of sound in air = 343 m/s).
A) 626 Hz
B) 600 Hz
C) 679 Hz
D) 577 Hz
E) 970 Hz

Free

Multiple Choice

Q 115Q 115

A police car siren emits a sound at 600 Hz. If an observer moves toward the source at
50 km/hr and hears a siren frequency of 678 Hz, calculate the speed of the police car and whether it is approaching or receding from the observer (assume the speed of sound in air = 343 m/s).
A) 99.0 km/hr receding
B) 144 km/hr approaching
C) 99.0 km/hr approaching
D) 144 km/hr receding
E) not possible for any reasonable police car speed

Free

Multiple Choice

Q 116Q 116

An observer is standing on the platform of a railway station. A train goes through the station without stopping. If the frequency of the train whistle decreases by a factor of 1.2 as it approaches and then passes him, calculate the speed of the train (assume the speed of sound in air = 343 m/s).
A) 112 km/hr
B) 31.2 km/hr
C) 56.0 km/hr
D) 62.0 km/hr
E) 122 km/hr

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Multiple Choice

Q 117Q 117

. A whistle is whirled around in a horizontal circle 120 times a minute at the end of a piece of string 1.5 m in length. If the standard frequency of the whistle is 550 Hz, calculate the difference between the highest and lowest frequencies heard by a stationary observer (assume the speed of sound in air = 343 m/s).
A) 58 Hz
B) 64 Hz
C) 61 Hz
D) 32 Hz
E) 29 Hz

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Multiple Choice

Q 118Q 118

Suppose the wavelength of the 656.3-nm line in the hydrogen spectrum is shifted to
656)8 nm for light from a particular star. What can you deduce for the speed of the star relative to us?
A) 914 km/s toward us
B) 457 km/s toward us
C) 914 km/s away from us
D) none of these answers
E) 457 km/s away from us

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Multiple Choice

Q 119Q 119

Suppose the apparent wavelength of the known lines in the spectrum of hydrogen are measured to increase by 50% when light from a distant galaxy is observed on Earth (this is known as the Red Shift). Calculate the speed of recession of the galaxy relative to Earth as a percentage of the speed of light.
A) 50%
B) 20%
C) 38%
D) 63%
E) 60%

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Multiple Choice

Q 120Q 120

An oscillator tuned to a frequency of 1 kHz is dropped from a tall building. How does the frequency picked up by a stationary observer at the top of the building change with time?
A) The frequency will be lower than 1 kHz but does not change with time.
B) The frequency will be lower than 1 kHz and decreases further with time.
C) The frequency will be higher than 1 kHz but does not change with time.
D) The frequency will be higher than 1 kHz and decreases further with time.
E) The frequency stays at 1 kHz.

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Multiple Choice

Q 121Q 121

The picture on the right represents the wavefronts of a supersonic flight. The angle = 40. If the speed of sound is 300 m/s, what is the speed of the plane?
A) 360 m/s
B) 330 m/s
C) 300 m/s
D) 390 m/s
E) 470 m/s

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Multiple Choice

Q 122Q 122

Which of the following wavefronts results from a supersonic flight?
A) (1)
B) (2)
C) (3)
D) (1) and (3)
E) they are all supersonic

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Multiple Choice