Question 1

A standing wave in a pipe has nodes that are 1.2 m apart. What is the wavelength of the wave?

Accepted Answer

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 
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

Question 2

When listening to tuning forks of frequency 256 Hz and 260 Hz, one hears the following number of beats per second:

Accepted Answer

A)  0 
B)  2 
C)  4 
D)  8 
E)  258 
A)  0 
B)  2 
C)  4 
D)  8 
E)  258

Question 3

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

Question 4

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

Question 5

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 6

The standard reference sound level is about:

Accepted Answer

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 
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

Question 7

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?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 8

The difference between transverse and longitudinal waves:

Accepted Answer

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 
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

Question 9

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:

Accepted Answer

A)  5 m 
B)  4 m 
C)  3 m 
D)  2 m 
E)  1 m 
A)  5 m 
B)  4 m 
C)  3 m 
D)  2 m 
E)  1 m

Question 10

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 11

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

Exam 17: Waves II

A standing wave in a pipe has nodes that are 1.2 m apart. What is the wavelength of the wave?

When listening to tuning forks of frequency 256 Hz and 260 Hz, one hears the following number of beats per second:

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:

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?

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 standard reference sound level is about:

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?

The difference between transverse and longitudinal waves:

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:

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:

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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?