Unit 4 Practice Test
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
____
1. The amplitude of a pendulum is doubled. This means:
a. the pendulum will swing twice as far away from the center.
b. the period of the pendulum will be twice as long.
c. the frequency of the pendulum will be twice as high.
d. the pendulum will have twice its original mass.
Figure 4.1
____
2. Which of the graphs in figure 4.1 has an amplitude of 10 centimeters?
a. Graph A
b. Graph B
c. Graph C
d. Graphs B and C
____
3. Which of the graphs in figure 4.1 has a period of two seconds?
a. Graph A
b. Graph B
c. Graph C
d. Graphs B and C
____
4. The diagram illustrating two waves in phase is:
____
a.
c.
b.
d.
5. Sound waves are always:
a. transverse waves.
b. longitudinal waves.
c. electromagnetic waves.
d. seismic waves.
____
6. Which of the following usually occurs inside a material instead of at the surface?
a. Reflection
b. Refraction
c. Diffraction
d. Absorption
____
7. Natural frequency is:
a. what happens when two waves combine to produce one wave of lower amplitude.
b. the frequency at which a system oscillates when it is disturbed.
c. the rate at which vibrations are naturally damped in an oscillator.
d. an oscillator whose frequency is a multiple of another wave.
____
8. The picture below shows five harmonics of a vibrating string experiment. The vibrating string
incorrectly labeled is:
a.
b.
c.
d.
1
2
3
4
____ 9. A decibel is a unit used to measure the:
a. pitch of sound.
b. color or complexity of sound.
c. loudness of sound.
d. frequency of a sound.
____ 10. The musical scale consists of a set of frequencies divided into "octaves" represented by letters A to
G. In the middle of the scale, middle C has a frequency of 264 hertz. The frequency of the "C" above
middle C is:
a. 132 hertz.
b. 264 hertz.
c. 272 hertz.
d. 528 hertz.
Matching
Match the following terms with the correct definition. There is one extra term that will not match any
of the definitions.
a. cycle
b. hertz
c. amplitude
d. period
e. wavelength
f. interference
____
____
____
____
____
11.
12.
13.
14.
15.
Time for one cycle to occur
A single unit of periodic motion
Distance from one point on a wave to the same point on the next wave
Unit of measurement for frequency (one cycle per second)
Happens when two or more waves interact
Match the following terms with the correct definition. There is one extra term that will not match any
of the definitions.
a. resonance
b. decibel
c. system
d. frequency
e. oscillator
f. harmonics
____
____
____
____
____
16.
17.
18.
19.
20.
Multiples of the fundamental
A group chosen to include all those things of interest to be studied
A system that shows harmonic motion
The maximum response to an oscillating force occurring at a natural frequency
Number of cycles that occur in one second
Short Answer
21. How are frequency and period related?
22. Which graphs represent two pendulums that are in phase?
Figure 4.1
23. What is the period of the pendulum whose motion is graphed in Figure 4.1?
24. What is the amplitude of the pendulum whose motion is graphed in Figure 4.1?
25. The pictures below represent vibrating guitar strings. Which picture shows a guitar string of one and
only one wavelength?
26.Two pulses are traveling on the same rope as shown in the diagram. As they meet, what type of interaction
will occur at their meeting point?
Problem
27. The distance between the crests of two waves on a lake is 2.0 meters. The waves break on the shore
every 5 seconds. How fast do the waves move on the surface of the water?
28. On a guitar, if the natural frequency of a 64 centimeter string is 140 hertz, what is the frequency of a
48 centimeter string?
Essay
29. Describe each of the following wave interactions using at least one complete sentence.
a.
b.
c.
d.
reflection
refraction
diffraction
absorption
30. State THREE pieces of evidence that allow us to refer to sound as a wave.
Unit 4 Practice Test
Answer Section
MULTIPLE CHOICE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
A
C
C
A
B
D
B
B
C
D
MATCHING
11.
12.
13.
14.
15.
D
A
E
B
F
16.
17.
18.
19.
20.
F
C
E
A
D
SHORT ANSWER
21.
22.
23.
24.
25.
26.
Frequency and period are inversely related.
A and C
0.5 seconds
30 centimeters
b
destructive interference
or
They cancel each other out.
PROBLEM
27. velocity = wavelength period
velocity = 2.0 m  5 sec
velocity = 0.4 m/sec
28. The string length is 1/2 of the wavelength of the sound produced. Since the velocity of the sound
wave on the string is constant, the frequency can be calculated as follows:
velocity = frequency  wavelength
velocity = 140 Hz  1.28 m
velocity = 179 m/sec, the original velocity.
frequency = velocity  wavelength
frequency = 179 m/sec  0.96 m
frequency = 186 Hz
ESSAY
29.
a. Reflection occurs as a wave meets a boundary and bounces off, traveling in a new direction.
b. Refraction occurs as a wave passes through a boundary. It may change wave direction.
c. Diffraction occurs when a wave travels around an obstacle or through an opening in a boundary.
Wave direction is usually changed.
d. Absorption occurs as the amplitude of the wave decreases when the wave passes into and through
a material.
30. Answers may vary. Correct answers include:
Sound shows evidence of interference and diffraction.
Sound can be reflected, refracted, and absorbed.
Sound has a wavelength that can be demonstrated.
Sound has a frequency that can be demonstrated.
The speed of sound is frequency  wavelength.
Resonance can be demonstrated using sound.