Deck 12: Waves

Question 1

The wave-related quantity algebraically equivalent to 1/f is:

A)
B) T
C) A
D)

Answer 1

T

Question 2

A wave is described by y = 10 sin (4.0 $\pi$ t - 6.0 $\pi$ x). If the equation is in SI units with the units suppressed, what is its frequency?

A) 6.0 Hz
B) 2/3 Hz
C) 3.0 Hz
D) 2.0 Hz

Answer 2

2.0 Hz

Question 3

Bats can detect small objects such as insects that are of a size approximately that of one wavelength. If bats emit a chirp at a frequency of 50 kHz, and the speed of sound waves in air is 330 m/s, what is the smallest size insect they can detect?

A) 1.5 mm
B) 3.7 mm
C) 5.5 mm
D) 6.6 mm

Answer 3

6.6 mm

Question 4

In SI units, which of the following equations represents a wave of amplitude A with frequency 500 Hz and wavelength 1.60 m?

A)
B)
C)
D)

Question 5

A wave is described by y = 10 sin (4.0 $\pi$ t - 6.0 $\pi$ x). If the equation is in SI units with the units suppressed, what is the wavelength of this wave?

A) 2/3 m
B) 1/3 m
C) 1/6 m
D) 0.50 m

Question 6

Which of the following media cannot support longitudinal waves?

A) aluminum
B) air
C) string
D) water

Question 7

Which of the following is an example of a longitudinal wave?

A) sound wave in air
B) wave traveling in a string
C) both a and b
D) neither a nor b

Question 8

A wave on a string has a wavelength of 0.90 m at a frequency of 600 Hz. If a new wave at a frequency of 300 Hz is established in this same string under the same tension, what is the new wavelength?

A) 2.7 m
B) 1.8 m
C) 0.45 m
D) 0.30 m

Question 9

A wave is described by y = 10 sin (4.0 $\pi$ t - 6.0 $\pi$ x). If the equation is in SI units with the units suppressed, what is its speed?

A) 2/3 m/s
B) 3/2 m/s
C) 1/6 m/s
D) 1/4 m/s

Question 10

As a gust of wind blows across a field of grain, a wave can be seen to move across the field as the tops of the plants sway back and forth. This wave is a:

A) transverse wave.
B) longitudinal wave.
C) polarized wave.
D) interference of waves.

Question 11

The wavelength of a traveling wave can be calculated if one knows the:

A) frequency.
B) speed and amplitude.
C) amplitude and frequency.
D) frequency and speed.

Question 12

For a wave on the ocean, the amplitude is:

A) the distance between crests.
B) the height difference between a crest and a trough.
C) one half the height difference between a crest and a trough.
D) how far the wave goes up on the beach.

Question 13

If the frequency of a traveling wave train is increased by a factor of four in a medium where the speed is constant, which of the following is the result?

A) amplitude is one fourth as big
B) amplitude is quadrupled
C) wavelength is quadrupled
D) wavelength is one fourth as big

Question 14

A wave produced by a simple harmonic driving force is called a _____ wave.

A) disturbance
B) periodic
C) transverse
D) longitudinal

Question 15

Waves propagate at 4.0 m/s along a stretched string. The end of the string is vibrated up and down once every 3.0 s. What is the wavelength of the waves that travel along the string?

A) 3.0 m
B) 12 m
C) 6.0 m
D) 2.7 m

Question 16

A traveling wave train has wavelength 1.0 m and speed 20 m/s. Find the wave frequency.

A) 0.025 Hz
B) 20 Hz
C) 40 Hz
D) 10 Hz

Question 17

Sound waves of a certain frequency in air having a wavelength of 1.9 m will have what wavelength in water? Take the speed of sound in air to be 340 m/s and in water to be 1490 m/s.

A) 0.57 m
B) 1.9 m
C) 8.3 m
D) 11 m

Question 18

If a radio wave has speed 3.00*10⁸ m/s and frequency 99.7 MHz, what is its wavelength?

A) 8.78 m
B) 1.50 m
C) 2.78 m
D) 3.01 m

Question 19

A musical tone, sounded on a piano, has a frequency of 820 Hz and a wavelength in air of 0.400 m. What is the wave speed?

A) 587 m/s
B) 328 m/s
C) 235 m/s
D) 170 m/s

Question 20

In SI units, a wave is represented by . What is the time required for a single wavelength to pass a fixed point by this wave?

A) 200 s
B) (2 /50) s
C) 0.010 s
D) 80 s

Question 21

A wave travels in a string at 60 m/s. A second string of 40% greater linear density has the same tension applied as in the first string. What will be the resulting wave speed in the second string?

A) also 60 m/s
B) 51 m/s
C) 72 m/s
D) 55 m/s

Question 22

Doubling the mass per unit length of a guitar string will result in changing the wave speed in the string by what factor?

A) 1.41
B) 1.00 (i.e., no change)
C) 0.71
D) 2.00

Question 23

Quadrupling both the tension in a guitar string and its mass per unit length will result in changing the wave speed in the string by what factor?

A) 4.00
B) 2.00
C) 1.00 (i.e., no change)
D) 0.50

Question 24

A 2.0-m long piano string of mass 40 g is under a tension of 338 N. Find the speed with which a wave travels on this string.

A) 130 m/s
B) 260 m/s
C) 520 m/s
D) 1040 m/s

Question 25

Two water waves meet at the same point, one having a displacement above equilibrium of 60 cm and the other having a displacement above equilibrium of 40 cm. At this moment, what is the resulting displacement above equilibrium?

A) 140 cm
B) 100 cm
C) 70 cm
D) Information about the amplitudes needs to be given to find an answer.

Question 26

Transverse waves travel with a speed of 283 m/s along a taut copper wire that has a diameter of 1.50 mm. What is the tension in the wire? (The density of copper is 8.93 g/cm³.)

A) 1890 N
B) 1260 N
C) 631 N
D) 315 N

Question 27

Equal wavelength waves of amplitude 0.25 m and 0.10 m interfere with one another. What is the resulting minimum amplitude that can result?

A) 0.15 m
B) 0.10 m
C) 0 m
D) -0.40 m

Question 28

A speaker designed to emit spherical sound waves is producing a sound intensity of 8 at a distance of 1 m from the speaker. What would be the intensity of this sound at a distance of 2 m from the speaker?

A)
B) 4
C)
D) 2

Question 29

A long string is pulled so that the tension in it increases by a factor of four. If the change in length is negligible, by what factor does the wave speed change?

A) 0.25
B) 0.50
C) 2.0
D) 4.0

Question 30

The superposition principle has to do with which of the following?

A) effects of waves at great distances
B) the ability of some waves to move very far
C) how displacements of interacting waves add together
D) relativistic wave behavior

Question 31

Consider two identical and symmetrical wave pulses on a string. Suppose the first pulse reaches the fixed end of the string and is reflected back and then meets the second pulse. When the two pulses overlap exactly, the superposition principle predicts that the amplitude of the resultant pulses, at that moment, will be what factor times the amplitude of one of the original pulses?

A) 0
B) 1
C) 2
D) 4

Question 32

Standing waves can result from _____ waves.

A) longitudinal
B) transverse
C) both longitudinal and transverse
D) neither longitudinal nor transverse

Question 33

What is the cause of refraction of a wave traveling from one medium to another?

A) There is a frequency change due to the change in the medium
B) There is a speed change due to the change in the medium.
C) There is a change in wave amplitude due to the change in the medium.
D) None of the above are associated with refraction.

Question 34

If the speed of a wave on a violin string is 400 m/s, what will be the speed of the wave if the tension in the string is halved?

A) 100 m/s
B) 200 m/s
C) 280 m/s
D) 570 m/s

Question 35

If a wave pulse is reflected from a free boundary, which of the following choices best describes what happens to the reflected pulse?

A) becomes inverted
B) remains upright
C) halved in amplitude
D) doubled in amplitude

Question 36

For a wave traveling in a string, by what factor would the tension need to be increased to triple the wave speed?

A) 2.7
B) 9.0
C) 3.0
D) 1.7

Question 37

What is the phase difference when two waves, traveling in the same medium, undergo constructive interference?

A) 270 $\degree$
B) 180 $\degree$
C) 90 $\degree$
D) 0 $\degree$

Question 38

A string is strung horizontally with a fixed tension. A wave of frequency 100 Hz is sent along the string, and it has a wave speed of 100 m/s. Then a second wave, one of frequency 200 Hz, is sent along the string. What is the wave speed of the second wave?

A) 25.0 m/s
B) 50.0 m/s
C) 70.7 m/s
D) 100 m/s

Question 39

A radar pulse is bounced off the Moon at a distance of 400,000 km. What is the time from the transmitting of the pulse until its return?

A) 1.28 s
B) 2.56 s
C) 2.67 s
D) 3.84 s

Question 40

A wave is traveling in a string at 60 m/s. When the tension is then increased 60%, what will be the resulting wave speed?

A) also 60 m/s
B) 76 m/s
C) 71 m/s
D) 55 m/s

Question 41

Which of the following seismic waves travels the slowest?

A) surface waves
B) pressure waves
C) shear waves
D) both surface and pressure waves

Question 42

A 100-m long high-voltage cable is suspended between two towers. The mass of the 100-m cable is 200 kg. If the tension in the cable is 20,000 N, what is the lowest frequency at which this cable can oscillate?

A) 0.50 Hz
B) 0.61 Hz
C) 0.75 Hz
D) 1.5 Hz

Question 43

A 1.5-m string is held fixed at both ends. When driven by a 180-Hz source, the string vibrates in 3 distinct segments. What is the natural fundamental frequency of the string?

A) 30 Hz
B) 60 Hz
C) 90 Hz
D) 540 Hz

Question 44

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

A) 3
B) 3^1/2
C) 3^-1/2
D) 1.5

Question 45

A C note (f = 128 Hz) is sounded on a piano. If the length of the piano wire is 1.00 m and its mass density is 5.00 g/m, what is the tension in the wire?

A) 84 N
B) 328 N
C) 655 N
D) 1310 N

Question 46

An earthquake emits both P waves and S waves that travel at different speeds through the Earth. Suppose a P wave travels at 8000 m/s and an S wave at 4000 m/s. If P waves are received at a seismic station 20.0 s before an S wave arrives, how far is the station from the earthquake center?

A) 80 km
B) 160 km
C) 240 km
D) 320 km

Question 47

If a guitar string has a fundamental frequency of 250 Hz, what is the frequency of its third harmonic?

A) 250 Hz
B) 750 Hz
C) 1000 Hz
D) 1500 Hz

Question 48

Are the P waves and the S waves associated with earthquakes transverse or longitudinal?

A) Both are transverse.
B) Both are longitudinal.
C) P waves are transverse, and S waves are longitudinal.
D) P waves are longitudinal, and S waves are transverse.

Question 49

A string of length L with fixed ends is made to go into standing wave patterns. What is the longest wavelength associated with all possible standing wave patterns in this situation?

A) L/4
B) L/2
C) L
D) 2L

Question 50

If the tension on a guitar string is increased by a factor of 2, the fundamental frequency at which it vibrates is changed by what factor?

A) 0.5
B) 2^1/2
C) 2^-1/2
D) 2

Question 51

A standing wave is set up in a 100-cm string fixed at both ends. The string vibrates in 5 distinct segments when driven by a 120-Hz source. What is the wavelength?

A) 10 cm
B) 20 cm
C) 40 cm
D) 80 cm

Question 52

A string with fixed ends is made to go into standing wave patterns. At a given tension, the lowest frequency for which such a pattern exists is 150 Hz. Which of the following frequencies would also cause a standing wave pattern in this case?

A) 250 Hz
B) 500 Hz
C) 750 Hz
D) All of the above frequencies will cause a standing wave pattern in this case.

Question 53

How many nodes does a standing wave in a string have at the frequency of the sixth harmonic?

A) 12
B) 6
C) 3
D) The answer is not given.

Question 54

If I double the mass per unit length of guitar string, its natural frequency changes by what factor?

A) 2.0
B) 1.4
C) 1.0
D) 0.71

Question 55

For a standing wave on a string, the wavelength must equal:

A) the distance between adjacent nodes.
B) the distance between adjacent antinodes.
C) twice the distance between adjacent nodes.
D) the distance between supports.

Question 56

The lowest A on a piano has a frequency of 27.5 Hz. If the tension in the 2.0-m long string is 151 N and one-half wavelength occupies the string, what is the mass of the string?

A) 100 g
B) 25 g
C) 37 g
D) 50 g

Question 57

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. This 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 by a factor of:

A) 4.0.
B) 2.0.
C) 1.4.
D) 1.0.

Question 58

A standing wave is set up in a 2.0-m string fixed at both ends. The string vibrates in 3 distinct segments when driven by a 120-Hz source. In how many distinct standing wave segments will the string vibrate if the tension is increased by a factor of 4?

A) 3
B) 6
C) 9
D) No standing wave pattern occurs.