Question 1

The speed of sound in air is 340 m/s, and the density of air is 1.2 kg/m3.If the displacement amplitude of a 440-Hz sound wave is 10 µm, what is the intensity of the wave?

Accepted Answer

A) 0.16 W/m2 
B) 0.32 W/m2 
C) 12 W/m2 
D) 16 W/m2 
E) 32 W/m2 
A) 0.16 W/m2 
B) 0.32 W/m2 
C) 12 W/m2 
D) 16 W/m2 
E) 32 W/m2 E

Question 2

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 fX::fY is:

Accepted Answer

A) 1:1 
B) 1:2 
C) 2:1 
D) 1:4 
E) 4:1 
A) 1:1 
B) 1:2 
C) 2:1 
D) 1:4 
E) 4:1 A

Question 3

The longitudinal displacement of a mass element in a medium as a sound wave passes through it is given by s = sm cos (kx - ωt).Consider a sound wave of frequency 440 Hz and wavelength 0.75m.If sm = 12 µm, what is the displacement of an element of air located at x = 1.2 m at time t = 0.11 s?

Accepted Answer

A) 3.7 µm 
B) 4.9 µm 
C) 6.0 µm 
D) 8.2 µm 
E) 12 µm 
A) 3.7 µm 
B) 4.9 µm 
C) 6.0 µm 
D) 8.2 µm 
E) 12 µm A

Question 4

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:

Accepted Answer

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 
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

Question 5

The speed of sound in air is 340 m/s, and the density of air is 1.2 kg/m3.If the displacement amplitude of a 440-Hz sound wave is 10 µm, what is its pressure-variation amplitude?

Accepted Answer

A) 1.8 Pa 
B) 3.3 Pa 
C) 11 Pa 
D) 15 Pa 
E) 28 Pa 
A) 1.8 Pa 
B) 3.3 Pa 
C) 11 Pa 
D) 15 Pa 
E) 28 Pa

Question 6

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:

Accepted Answer

A) 4.2 cm 
B) 8.3 cm 
C) 17 cm 
D) 33 cm 
E) 66 cm 
A) 4.2 cm 
B) 8.3 cm 
C) 17 cm 
D) 33 cm 
E) 66 cm

Question 7

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):

Accepted Answer

A) 5800 m 
B) 6100 m 
C) 8400 m 
D) 12,000 m 
E) 16,000 m 
A) 5800 m 
B) 6100 m 
C) 8400 m 
D) 12,000 m 
E) 16,000 m

Question 8

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?

Accepted Answer

A) intensity 
B) fundamental frequency 
C) displacement amplitude 
D) pressure amplitude 
E) harmonic content 
A) intensity 
B) fundamental frequency 
C) displacement amplitude 
D) pressure amplitude 
E) harmonic content

Question 9

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:

Accepted Answer

A) 290 Hz 
B) 540 Hz 
C) 1000 Hz 
D) 1800 Hz 
E) 3400 Hz 
A) 290 Hz 
B) 540 Hz 
C) 1000 Hz 
D) 1800 Hz 
E) 3400 Hz

Question 10

A tuning fork produces sound waves of wavelength $\lambda$ 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:

Accepted Answer

A) "$\lambda$/4" 
B) "2$\lambda$/4" 
C) "3$\lambda$/4" 
D) "5$\lambda$/4" 
E) "7$\lambda$/4" 
A) "$\lambda$/4" 
B) "2$\lambda$/4" 
C) "3$\lambda$/4" 
D) "5$\lambda$/4" 
E) "7$\lambda$/4"

Question 11

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:

Accepted Answer

A) 20 m/s 
B) 51 m/s 
C) 102 m/s 
D) 205 m/s 
E) 410 m/s 
A) 20 m/s 
B) 51 m/s 
C) 102 m/s 
D) 205 m/s 
E) 410 m/s

Question 12

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:

Accepted Answer

A) 14 Hz 
B) 28 Hz 
C) 57 Hz 
D) 110 Hz 
E) 230 Hz 
A) 14 Hz 
B) 28 Hz 
C) 57 Hz 
D) 110 Hz 
E) 230 Hz

Question 13

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?

Accepted Answer

A) The fundamental 
B) The second 
C) The third 
D) The fourth 
E) There are none 
A) The fundamental 
B) The second 
C) The third 
D) The fourth 
E) There are none

Question 14

To produce beats it is necessary to use two waves:

Accepted Answer

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 
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

Question 15

If the speed of sound is 340 m/s, the shortest pipe, closed at one end, which resonates at 218 Hz is:

Accepted Answer

A) 39 cm 
B) 78 cm 
C) 1.6 m 
D) 3.1 m 
E) 6.2 m 
A) 39 cm 
B) 78 cm 
C) 1.6 m 
D) 3.1 m 
E) 6.2 m

Question 16

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:

Accepted Answer

A) -2 db 
B) +2 db 
C) +10 db 
D) +20 db 
E) +100 db 
A) -2 db 
B) +2 db 
C) +10 db 
D) +20 db 
E) +100 db

Question 17

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:

Accepted Answer

A) 58 Hz 
B) 500 Hz 
C) 1000 Hz 
D) 2000 Hz 
E) 5800 Hz 
A) 58 Hz 
B) 500 Hz 
C) 1000 Hz 
D) 2000 Hz 
E) 5800 Hz

Question 18

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:

Accepted Answer

A) "0° (no shock wave) 
B) "32 ° " 
C) "40 ° " 
D) "50 ° " 
E) "58 ° " 
A) "0° (no shock wave) 
B) "32 ° " 
C) "40 ° " 
D) "50 ° " 
E) "58 ° "

Question 19

What is a wavefront?

Accepted Answer

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. 
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.

Question 20

The sound intensity 5.0 m from point source is 0.50 W/m2.The power output of the source is:

Accepted Answer

A) 12.5 W 
B) 39 W 
C) 79 W 
D) 160 W 
E) 260 W 
A) 12.5 W 
B) 39 W 
C) 79 W 
D) 160 W 
E) 260 W

Exam 17: Waves

The speed of sound in air is 340 m/s, and the density of air is 1.2 kg/m3.If the displacement amplitude of a 440-Hz sound wave is 10 µm, what is the intensity of the wave?

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 fX::fY is:

The longitudinal displacement of a mass element in a medium as a sound wave passes through it is given by s = sm cos (kx - ωt).Consider a sound wave of frequency 440 Hz and wavelength 0.75m.If sm = 12 µm, what is the displacement of an element of air located at x = 1.2 m at time t = 0.11 s?

The speed of sound in air is 340 m/s, and the density of air is 1.2 kg/m3.If the displacement amplitude of a 440-Hz sound wave is 10 µm, what is its pressure-variation amplitude?

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:

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 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 tuning fork produces sound waves of wavelength λ\lambdaλ 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 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:

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:

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?

To produce beats it is necessary to use two waves:

If the speed of sound is 340 m/s, the shortest pipe, closed at one end, which resonates at 218 Hz is:

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 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:

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:

What is a wavefront?

The sound intensity 5.0 m from point source is 0.50 W/m2.The power output of the source is:

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The speed of sound in air is 340 m/s, and the density of air is 1.2 kg/m³.If the displacement amplitude of a 440-Hz sound wave is 10 µm, what is the intensity of the wave?

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:

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?

The speed of sound in air is 340 m/s, and the density of air is 1.2 kg/m³.If the displacement amplitude of a 440-Hz sound wave is 10 µm, what is its pressure-variation amplitude?

A tuning fork produces sound waves of wavelength $\lambda$ 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:

The sound intensity 5.0 m from point source is 0.50 W/m².The power output of the source is: