Ch 26: Sound Review 2
Short Answers
1. What is the source of all sound?
a. All sounds originate in the vibrations of material objects.
2. How does a sound wave travel through air?
a. As a source of sound vibrates, a series of compressions and rarefactions travels outward from the
source.
3. What media transmit sound?
a. Sound travels in solids, liquids, and gases.
4. What determines the speed of sound in a medium?
a. The speed of sound in a gas depends on the temperature of the gas and the mass of the particles
in the gas.
b. The speed of sound in a material depends on the material’s elasticity.
5. How far away is a storm if you note a 3-second delay between a lightning flash and the sound of thunder?
a. For a speed of sound in air of 340 m/s, the distance is
(340 m/s) × (3 s) = about 1000 m or 1 km. Time for the light is negligible, so the storm is about 1
km away.
6. What happens when an elastic material is disturbed?
a. When any object composed of an elastic material is disturbed, it vibrates at its own special set of
frequencies, which together form its special sound.
7. What causes resonance?
a. An object resonates when there is a force to pull it back to its starting position and enough energy
to keep it vibrating.
8. What are the effects of constructive and destructive interference?
a. When constructive interference occurs with sound waves, the listener hears a louder sound. When
destructive interference occurs, the listener hears a fainter sound or no sound at all.
9. What causes beats?
a. When two tones of slightly different frequency are sounded together, a regular fluctuation in the
loudness of the combined sounds is heard.
10. What is the beat frequency when a 262-Hz and a 266-Hz tuning fork are sounded together?
a. The 262-Hz and 266-Hz forks will produce 4 beats per second, that is, 4 Hz
Multiple Choice
1. The sound waves that humans cannot hear are those with frequencies
a. from 20 to 20,000 Hz.
b. below 20 Hz.
Answer: D
2. Sound travels in air by a series of
a. compressions.
b. rarefactions.
Answer: C
c. above 20,000 Hz.
d. both B and C
c. both compressions and
rarefactions.
d. pitches.
3. Sound travels faster in
a. a vacuum compared to liquids.
b. gases compared to liquids.
c. gases compared to solids.
d. solids compared to gases.
Answer: D
4. The speed of sound varies with
a. amplitude.
b. frequency.
c. temperature.
d. pitch.
Answer: C
5. The loudness of a sound is most closely related to its
a. frequency.
b. period.
c. wavelength.
d. intensity.
Answer: D
6. When you tap various objects they produce characteristic sounds that are related to
a. wavelength.
c. period.
b. amplitude.
d. natural frequency.
Answer: D
7. When the surface of a guitar is made to vibrate we say it undergoes
a. forced vibration.
b. resonance.
c. refraction.
d. amplitude reduction.
Answer: A
8. When an object is set into vibration by a wave having a frequency that matches the natural frequency of the
object, what occurs is
a. forced vibration.
c. refraction.
b. resonance.
d. amplitude reduction.
Answer: B
9. Noise-canceling devices such as jackhammer earphones make use of sound
a. destruction.
c. resonance.
b. interference.
d. amplification.
Answer: B
10. The phenomenon of beats is the result of sound
a. destruction.
b. interference.
Answer: B
c. resonance.
d. amplification.
11. If the energy in a longitudinal wave travels from south to north, the particles of the medium ____.
a. move from north to south, only.
b. vibrate both north and south.
c. move from east to west, only.
d. vibrate both east and west.
Answer: B
12. A transverse wave is traveling through a medium. See diagram below. The particles of the medium are
moving.
a. parallel to the line joining AD.
b. along the line joining CI.
c. perpendicular to the line joining AD.
d. at various angles to the line CI.
Answer: A
13. The main factor which effects the speed of a sound wave is the ____.
a. amplitude of the sound wave
b. intensity of the sound wave
c. loudness of the sound wave
d. properties of the medium
e. pitch of the sound wave
Answer: D
14. As a wave travels into a medium in which its speed increases, its wavelength ____.
a. decreases
b. increases
c. remains the same
Answer: B
15. The ____ is defined as the number of cycles of a periodic wave occurring per unit time.
a. wavelength
b. period
c. amplitude
d. frequency
Answer: D
16. Many wave properties are dependent upon other wave properties. Yet, one wave property is independent of
all other wave properties. Which one of the following properties of a wave is independent of all the others?
a. wavelength
Answer: D
b. frequency
c. period
d. velocity
17. A vibrating object with a frequency of 200 Hz produces sound which travels through air at 360 m/s. The
number of meters separating the adjacent compressions in the sound wave is ____.
a. 0.90
b. 1.8
c. 3.6
d. 7.2
e. 200
Answer: B
18. If two crests meet while passing through the same medium, then constructive interference occurs.
a. True
b. False
Answer: A
19. A node is a point along a medium where there is always ____.
a. a crest meeting a crest
b. a trough meeting a trough
d. destructive interference
e. a double rarefaction.
c. constructive interference
Answer: D
20. It is possible that one vibrating object can set another object into vibration if the natural frequencies of the
two objects are the same.
a. True
b. False
Answer: A
21. A standing wave experiment is performed to determine the speed of waves in a rope. The standing wave
pattern shown below is established in the rope. The rope makes 90.0 complete vibrational cycles in exactly
one minute. The speed of the waves is ____ m/s.
a. 3.0
b. 6.0
c. 180
d. 360
e. 540
Answer: B
22. The distance between successive nodes in any standing wave pattern is equivalent to ____ wavelengths.
a. 1/4
Answer: B
b. 1/2
c. 3/4
d. 1
e. 2.
23. A 20.0-cm long pipe is covered at one end in order to create a closed-end air column. A vibrating tuning fork
is held near its open end, forcing the air to vibrate in its first harmonic. The wavelength of the standing wave
pattern is ____.
a. 5.0 cm
b. 10.0 cm
c. 20.0 cm
d. 40.0 cm
e. 80.0 cm
Answer: E
24. The diagrams represent four different standing wave patterns in air columns of equal length. Which of the
columns will produce the note having the highest pitch?
a. A
b. B
c. C
d. D
e. All column produce notes having the same pitch
Answer: D
25. In order for two sound waves to produce audible beats, it is essential that the two waves have ____.
a. the same amplitude
b. the same frequency
c. the same number of overtones
d. slightly different amplitudes
e. slightly different frequencies
Answer: E
26. Two tuning forks with frequencies of 256 Hz and 258 Hz are sounded at the same time. Beats are observed;
2 beats will be heard in 2 s.
a. True
Answer: B
b. False