A 100-m long high-voltage cable is suspended between two towers. The mass of the 100-m cable is 150 kg. If the tension in the cable is 30,000 N, what is the lowest frequency at which this cable can oscillate?

1
A 100-m long high-voltage cable is suspended
between two towers. The mass of the 100-m cable
is 150 kg. If the tension in the cable is 30,000
N, what is the lowest frequency at which this
cable can oscillate?

1. 0.7 Hz
2. 1.0 Hz
3. 1.4 Hz
4. 2.0 Hz

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2
A standing wave is set up in a 200 cm length
string fixed at both ends. The string vibrates in
5 distinct segments when driven by a 120 Hz
source. What is the wavelength?

1. 10 cm
2. 20 cm
3. 40 cm
4. 80 cm

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3
Two loudspeakers are placed side by side and
driven by the same source at 500 Hz. A listener
is positioned in front of the two speakers and
on the line separating them, thus creating a
constructive interference at the listener's ear.
If one of the speakers is gradually pushed toward
the listener, how far must it be moved to repeat
the condition of constructive interference at the
listener's ear? (The speed of sound 340 m/s)

1. 1.02 m
2. 0.68 m
3. 0.34 m
4. 0.17 m

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4
A standing wave is set up in a 2.0 m length
string fixed at both ends. The string vibrates in
5 distinct segments when driven by a 120 Hz
source. What is the natural fundamental frequency
of the string?

1. 24 Hz
2. 48 Hz
3. 240 Hz
4. 600 Hz

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5
A standing wave is set up in a 2.0 m length
string fixed at both ends. The string vibrates in
5 distinct segments when driven by a 120 Hz
source. In how many distinct standing wave
segments would the same string vibrate if the
tension were increased by A factor of 4?

1. 3
2. 10
3. 20
4. No standing wave pattern occurs.

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6
If a 1000 Hz sound source moves at a speed of
50.0 m/s toward a listener who moves at a speed
of 30.0 m/s in a direction away from the source,
what is the apparent frequency heard by the
listener? (The velocity of sound is 340 m/s.)

1. 937 Hz
2. 947 Hz
3. 1060 Hz
4. 1070 Hz

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7
The density of a certain metal solid is 7.2 x 103
kg/m3 and its Young's modulus is 10 x 1010
N/m2 . What is the velocity of sound in this
metal?

1. 1.4 x 107 m/s
2. 5900 m/s
3. 3700 m/s
4. 3000 m/s

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8
If one-third of the members of a symphony
orchestra are absent because of head colds, thus
reducing the overall intensity of sound by 33,
what will be the reduction in the decibel level?

1. 30 dB
2. 3 dB
3. 48 dB
4. 1.7 dB

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9
Two loudspeakers are placed next to each other
and driven by the same source at 500 Hz. A
listener is positioned in front of the two
speakers and on the line separating them, thus
creating a constructive interference at the
listener's ear. What minimum distance would one
of the speakers be moved back away from the
listener to produce destructive interference at
the listener's ear? (The speed of sound 340 m/s)

1. 1.36 m
2. 0.68 m
3. 0.34 m
4. 0.17 m

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10
If a sound source, with a 1000 Hz frequency,
moves with a speed of 50.0 m/s toward a listener
who is at rest, what is the apparent frequency as
heard by the listener? (The velocity of sound
340 m/s.)

1. 853 Hz
2. 872 Hz
3. 1150 Hz
4. 1170 Hz

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11
What is the intensity of a sound with a measured
intensity level of 84 dB? (I0 1012 watt/m2 )

1. 8.4 x 10-3 watts/m2
2. 2.5 x 10-4 watts/m2
3. 1.2 x 10-5 watts/m2
4. 7.4 x 10-4 watts/m2

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12
If the distance between a point sound source and
a dB detector is increased by a factor of 4, what
will be the reduction in intensity level?

1. 16 dB
2. 12 dB
3. 4 dB
4. 0.5 dB

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13
The speed of sound at 0C is 331 m/s. What is the
speed of sound at 25C? (0C 273 K)

1. 346 m/s
2. 356 m/s
3. 343 m/s
4. 350 m/s

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14
When you are standing by the railroad tracks, a
train passes by. The 1000 Hz frequency you hear
on approach changes to 800 Hz as it goes away.
How fast is the train moving? (The velocity of
sound 340 m/s.)

1. 15.67 m/s
2. 21.17 m/s
3. 28.0 m/s
4. 37.78 m/s

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15
What is the intensity level of a sound with
intensity of 5 x 1010 watts/m2 ? (I0 1012
watt/m2 )

1. 74 dB
2. 54 dB
3. 2.7 dB
4. 27 dB

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16
Tripling the tension in a guitar string will
change its natural frequency by what factor?

1. 0.58
2. 1.0
3. 1.7
4. 3.0

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17
Tripling the mass per unit length of a guitar
string will change its natural frequency by what
factor?

1. 0.58
2. 1.0
3. 1.7
4. 3.0

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18
The lower A on a piano has a frequency of 27.5
Hz. If the tension in the 2-m long string is 304
N and one-half wavelength occupies the string,
what is the mass of the string?

1. 100 grams
2. 25 grams
3. 37 grams
4. 50 grams

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19
A vibrating guitar string emits a tone
simultaneously with one from a 500 Hz tuning
fork. If a beat frequency of 5 Hz results, what
is the frequency of vibration of the string?

1. 505 Hz
2. 495 Hz
3. Both 505 Hz and 495 Hz are valid.
4. 2500 Hz

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20
What is the lowest frequency that will resonate
in a 2 m length organ pipe, closed at one end?
The speed of sound in air is 340 m/s.

1. 42.5 Hz
2. 85 Hz
3. 170 Hz
4. 680 Hz

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21
What is the first overtone frequency for a 2 m
length organ pipe, closed at one end? The speed
of sound in air is 340 m/s.

1. 42.5 Hz
2. 85 Hz
3. 127 Hz
4. 680 Hz

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22
If a guitar string has a fundamental frequency of
500 Hz, what is the frequency of its second
overtone?

1. 250 Hz
2. 750 Hz
3. 1000 Hz
4. 1500 Hz

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23
Two vibrating tuning forks, held side by side,
will create a beat frequency of what value if the
individual frequencies of the two forks are 342
Hz and 345 Hz, respectively?

1. 687 Hz
2. 343.5 Hz
3. 339 Hz
4. 3 Hz

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24
A train station bell gives off a fundamental tone
of 500 Hz as the train approaches the station at
a speed of 20 m/s. If the velocity of sound in
air is 335 m/s, what will be the apparent
frequency of the bell to an observer riding the
train?

1. 532 Hz
2. 530 Hz
3. 470 Hz
4. 472 Hz

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25
A standing wave set up in a 2.5 m long organ
pipe, open at both ends, will have a fundamental
tone with what wavelength?

1. 1.25 m
2. 2.5 m
3. 5.0 m
4. 6.25 m

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26
When a sound wave moves through a medium such as
air, the motion of the molecules making up the
medium is in what direction with respect to the
motion of the sound wave?

1. parallel
2. anti-parallel
3. both parallel and anti-parallel are valid.
4. perpendicular

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27
The velocity of sound in air is a function of
which one of the following?

1. wavelength
2. frequency
3. temperature
4. amplitude

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28
Doubling the power output from a sound source
emitting a single frequency will result in what
increase in loudness?

1. 0.5 dB
2. 2.0 dB
3. 3.0 dB
4. 20 dB

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29
Tripling the distance between sound source and a
listener will change the intensity, as detected
by the listener, by what factors?

1. 1/9
2. 0.33
3. 3.0
4. 9.0

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30
A sound wave with a speed of 334 m/s and a
wavelength of 3.0 m has what frequency?

1. 1000 Hz
2. 337 Hz
3. 111 Hz
4. 1/111 Hz

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31
The trough of the sine curve used to represent a
sound wave corresponds to which of the below?

1. condensation
2. rarefaction
3. point where molecules vibrate at a right angle to
   the direction of wave travel
4. region of low elasticity

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32
A series of ocean waves, each 5.0 m from crest to
crest, moving past the observer at a rate of 2
waves per second, have what velocity?

1. 2.5 m/s
2. 5.0 m/s
3. 8.0 m/s
4. 10.0 m/s

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33
If the tension on a guitar string is increased by
a factor of 3, the fundamental frequency at which
it vibrates is changed by what factor?

1. 9
2. 3
3. v3
4. 1/ v3

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34
What phenomenon is created by two tuning forks,
side by side, emitting frequencies which differ
by only a small amount?

1. resonance
2. interference
3. the Doppler effect
4. beats

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35
The number of overtones, and their relative
intensities, is associated with what property of
the tone generated by a musical instrument?

1. quality
2. interference pattern
3. range
4. attack pattern

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36
The Doppler shift of ultrasonic waves can measure
the velocity of blood in an artery. If the
frequency of the stationary source is 100 kHz and
the reflected sound has a Doppler shift of 200
Hz, what is the blood flow speed? (The speed of
sound in the body is 1500 m/s.)

1. 1.0 m/s
2. 1.5 m/s
3. 2.2 m/s
4. 3.3 m/s

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37
A bat, flying at 5 m/s, emits a chirp at 50 kHz.
If this sound pulse is reflected by a wall, what
is the frequency of the echo received by the bat?
(Vsound 340 m/s2 )

1. 51.5 kHz
2. 51.2 kHz
3. 40.8 kHz
4. 50.5 kHz

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38
A very loud train whistle has an acoustic power
output of 100 Watts. If the sound energy spreads
out spherically, what is the intensity level in
dB at a distance of 100 meters from the train?
(I0 10-12 W/m2 )

1. 78.3 dB
2. 81.6 dB
3. 89.0 dB
4. 95.0 dB

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39
How far away is a lightning strike if you hear
the thunderclap 3 s after you see the lightning
bolt strike? (Vsound 340 m/s, Vlight 3 x
108 m/s)

1. 113 m
2. 340 m
3. 680 m
4. 1020 m

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40
A low C (f 65 Hz) is sounded on a piano. If the
length of the piano wire is 2 m and its mass
density is 5 g/m, what is the tension of the wire?

1. 84 N
2. 168 N
3. 338 N
4. 677 N

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41
What is the intensity of sound (in W/m2 ) from a
rock band with a sound level of 120 dB? (I0
10-12 W/m2 )

1. 1 W/m2
2. 1.2 W/m2
3. 10 W/m2
4. 12 W/m2

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42
In the afternoon, the decibel level of a busy
freeway is 80 dB with 100 cars passing a given
point every minute. Late at night, the traffic
flow is only 5 cars per minute. What is the
late-night decibel level?

1. 77 dB
2. 74 dB
3. 70 dB
4. 67 dB

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43
The intensity level of sound 20 m from a jet
airliner is 120 dB. At what distance from the
airplane will the sound intensity level be at a
tolerable level of 100 dB? (Assume spherical
spreading of sound.)

1. 90 m
2. 120 m
3. 150 m
4. 200 m

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44
A flute behaves like a tube open at both ends. If
its length is 65.3 cm, and the velocity of sound
is 340 m/s, what is its fundamental frequency in
Hz?

1. 130 Hz
2. 159 Hz
3. 212 Hz
4. 260 Hz

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45
I stretch a rubber band and "plunk" it to make it
vibrate in its fundamental frequency. I then
stretch it to twice its length and make it
vibrate in the fundamental frequency once again.
If the rubber band is made so that doubling its
length doubles the tension and reduces the mass
per unit length by a factor of 2, the new
frequency will be related to the old frequency by
what factor?

1. 1.0
2. 1.4
3. 2.0
4. 4.0

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46
If two adjacent frequencies of an organ pipe
closed at one end are 550 Hz and 650 Hz, what is
the length of the organ pipe? (vsound 340 m/s)

1. 0.85 m
2. 1.25 m
3. 1.50 m
4. 1.70 m

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47
For a standing wave in an air column in a pipe
that is open at both ends, there must be at least

1. one node and one antinode
2. two nodes and one antinode
3. two antinodes and one node
4. two nodes and two antinodes

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48
Two notes have a beat frequency of 4 Hz. The
frequency of one note is 420 Hz. What is the
frequency of the other note?

1. 422 Hz or 418 Hz
2. 105 Hz
3. 424 Hz or 416 Hz
4. 1680 Hz

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49
While standing at a crosswalk, you hear a
frequency of 560 Hz from an approaching police
car. After the police car passes, its frequency
is 480 Hz. Given the speed of sound is 340 m/s,
what is the velocity of the police car?

1. 13.2 m/s
2. 17.4 m/s
3. 21.1 m/s
4. 26.4 m/s

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50
As a train starts from rest and then accelerates
down the track, coming toward me faster and
faster, the speed of the sound waves coming
toward me will be

1. slower than the normal speed of sound in air.
2. equal to the normal speed of sound in air.
3. some constant speed faster than the normal speed
   of sound in air.
4. faster and faster.

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51
An airplane flying with a constant velocity flies
from a cold air mass into a warm air mass. The
Mach number will

1. increase.
2. decrease.
3. stay the same.
4. become unstable.

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52
When I stand half way between two speakers, with
one on my left and one on my right, a musical
note from the speakers gives me constructive
interference. How far to my left should I move to
obtain destructive interference?

1. one-fourth of a wavelength
2. half a wavelength
3. one wavelength
4. one and a half wavelengths

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53
If the intensity of a sound is increased by a
factor of 100, how is the decibel level changed?
The new decibel level will be

1. two units greater
2. double the old one
3. ten times greater
4. twenty units greater

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54
For a standing wave on a string the wavelength
must equal

1. the distance between adjacent nodes
2. the distance between adjacent antinodes
3. twice the distance between adjacent nodes
4. the distance between supports

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55
A tuning fork is sounded above a resonating tube
(one end closed) which resonates at a length of
0.20 m and again at 0.60 m. If the tube length
were extended further, at what point will the
tuning fork again create a resonance condition?

1. 0.8 m
2. 1.0 m
3. 1.2 m
4. 1.6 m

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56
Consider a vibrating string that makes a sound
wave that moves through the air. As the guitar
string moves up and down, the air molecules that
are a certain horizontal distance from the string
will move

1. up and down
2. toward and away from the guitar string
3. back and forth along the direction of the length
   of the string.
4. in circles around the guitar string

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57
If I0 10-12 W/m2 is the threshold of
hearing, a sound with intensity I1 10-11 W/m2
will give a certain decibel level. Suppose a new
sound has an intensity I2 I12 /I0 . What is
the new decibel level?

1. 2.0
2. 20
3. 100
4. it will square the decibel level

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58
A tuning fork is sounded above a resonating tube
(one end closed) which resonates at a length of
0.20 m and again at 0.60 m. What is the frequency
of the fork when the speed of sound is taken to
be 340 m/s?

1. 567 Hz
2. 425 Hz
3. 1700 Hz
4. 950 Hz

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