Deck 8: The Waves

Question 1

Wind waves in the open sea have wavelengths and speeds that are defined by the wave period.

Answer 1

True

Question 2

The diameter of deep-water wave orbits decrease with depth.

Answer 2

True

Question 3

When deep-water waves travel away from a storm, the longer waves move faster than the shorter waves. This process is called sorting, or ________.

Answer 3

dispersion

Question 4

The restoring force of a capillary wave is gravity.

Question 5

The equation C = gT/2л is appropriate to determine the speed of a deep-water wave.

Question 6

Storm waves in the open sea are likely to be less steep and break less often than waves in the surf zone.

Question 7

A ________ is a wave generated by a submarine earthquake.

Question 8

Shallow-water waves will change direction as they approach shore in a process called ________.

Question 9

Water particles in shallow-water waves move in ________ orbits.

Question 10

More than half of the tsunami warnings issued in the last 50 years have been false alarms.

Question 11

Waves that form beneath the surface on the pycnocline are called ________ waves.

Question 12

A 10 m long wave will have elliptical orbits in water that are 50 m deep.

Question 13

The restoring force for ________ waves is surface tension.

Question 14

Water particles in deep-water waves move in ________ orbits.

Question 15

Water particle orbits of shallow-water waves change only their vertical dimension with depth.

Question 16

Waves that travel through each other tend to cancel each other out and cease to exist on the far side of the passing zone.

Question 17

A tsunami is a shallow water wave.

Question 18

The speed of a shallow water wave changes with depth, but the length of a wave does not change.

Question 19

Internal waves are always standing waves.

Question 20

A tsunami, or seismic sea wave, travels at a speed determined by the size of the earthquake that forms it.

Question 21

The speed of a surface gravity wave is described by the ________.

A) wavelength times the period
B) wave period divided by wavelength
C) wavelength divided by wave period
D) square of the depth
E) Earth's gravity

Question 22

The period of a wave never changes.

Question 23

The orbital motion of a deep-water wave extends to a depth equal to ________.

A) twice the wavelength
B) the wave's height
C) one-half the wavelength
D) one-half the wave's height
E) the seafloor depth

Question 24

The wave frequency is the time it takes for two subsequent wave crests to pass a location.

Question 25

A group of waves is propagated at a speed that is ________ the speed of the individual waves in deep water.

A) twice
B) the same as
C) one-half
D) one-quarter
E) one-tenth

Question 26

Tsunami are always deep-water waves.

Question 27

The diameter of wave orbitals increases with increasing depth.

Question 28

Because of dispersion, the distribution of waves from a single storm changes with time and distance from the storm center.

Question 29

There is no vertical motion at the antinode of a standing wave.

Question 30

If a surface water wave has a wavelength of 200 m and a 5-second period, its speed is ________.

A) 4000 cm/sec
B) 400 cm/sec
C) 40 cm/sec
D) 100 m/sec
E) 10 m/sec

Question 31

Wavelength is the distance from the crest to the trough of the same wave.

Question 32

On a standing wave, the maximum vertical movement occurs at the node.

Question 33

The most common generating force for water waves is wind.

Question 34

The maximum diameter of a water particle orbit of a deep water wave is defined by wave ________.

A) steepness
B) height
C) length
D) period
E) speed

Question 35

Shorter period waves travel faster than longer period waves.

Question 36

There are three antinodes in a double-node standing wave.

Question 37

The restoring force of a fully developed wind wave is ________.

A) gravity
B) solar heat
C) density
D) surface tension
E) viscosity

Question 38

When the water depth is between L/2 and L/20, the wave speed is constant.

Question 39

Constructive interference between waves increases the height of the resulting wave.

Question 40

Internal waves are faster and have shorter periods than most wind waves.

Question 41

Swell is more regular than waves in the wind-generated area because ________.

A) waves have been sorted by dispersion
B) some small waves have been damped out by friction
C) packets of swell are all at the same depth at the same time
D) waves have been sorted by dispersion and some small waves have been damped out by friction
E) waves have been sorted by dispersion, some small waves have been damped out by friction, and packets of swell are all at the same depth at the same time

Question 42

If a wave is a capillary wave, the force that causes the water to return to its undisturbed level is ________.

A) gravity
B) wind
C) seismic forces
D) surface tension
E) All of these are correct.

Question 43

Waves moving against a current will ________.

A) increase their height
B) decrease their speed
C) shorten their wavelength
D) All of these are correct.
E) None of these is correct.

Question 44

The speed of a shallow water wave varies with ________.

A) its height
B) the depth of the water
C) its steepness
D) its period
E) its amplitude

Question 45

Water transported shoreward in the surf zone is returned seaward by ________.

A) shallow water waves
B) reflected waves
C) refracted waves
D) rip currents
E) internal waves

Question 46

Wave height of wind waves depends on ________.

A) wavelength
B) wind speed and duration
C) fetch
D) wavelength and wind speed and duration
E) wind speed and duration and fetch

Question 47

The amplitude of a wave is about ________ the wave height.

A) one-fourth
B) one-half
C) the same as
D) twice
E) four times

Question 48

In a standing wave, the positions where there is maximum vertical motion are called ________.

A) antinodes
B) nodes
C) wave gaps
D) troughs
E) surges

Question 49

Water protected from direct wave influence behind a breakwater can be placed in motion by wave ________.

A) diffraction
B) refraction
C) reflection
D) All of these are correct.
E) None of these is correct.

Question 50

The average energy of a wave is related to the square of its ________.

A) height
B) wave length
C) period
D) speed
E) All of these are correct.

Question 51

In a closed basin, a single-node standing wave oscillation tends to have a wavelength that is ________ the basin length.

A) one-quarter
B) one-half
C) the same as
D) twice
E) four times

Question 52

A wave with a height of 4 feet will have ________ as much energy as a 2-foot wave.

A) two times
B) four times
C) six times
D) eight times
E) ten times

Question 53

The speed of a shallow water wave is computed using ________.

A) C = the square root of gD
B) C² = gL/2л
C) C² = L/T
D) C = L × T
E) C = LT/g

Question 54

When waves arrive at monitoring stations set up long distances from a storm center, which waves arrive first?

A) Long-period waves
B) Short-period waves
C) Steeper waves
D) Internal waves
E) Capillary waves

Question 55

Two different wave groups with the same height travel together in the same direction. The wavelength of one group is twice as long as the wavelength of the other group. A combined wave of extra height will be produced ________.

A) every wave
B) every other wave
C) every third wave
D) every fifth wave
E) every seventh wave

Question 56

The average energy of a wave is determined by the wave's ________.

A) speed
B) length
C) period
D) All of these are correct.
E) None of these is correct.

Question 57

The refraction of waves tends to concentrate wave energy ________ and disperse energy ________.

A) in bays; on headlands
B) on headlands; in bays
C) along coasts; behind breakwaters
D) along coasts; on headlands
E) along coasts; in bays

Question 58

Water particle orbits for a shallow water wave are ________.

A) elliptic and flatten with depth
B) elliptic and enlarge with depth
C) circular and extend halfway to the seafloor
D) circular at the surface and elliptical at the sea floor
E) circular and extend to the seafloor

Question 59

Waves occurring at the interface between layers of seawater and fresh water are called ________.

A) freshwater waves
B) interference waves
C) density waves
D) internal waves
E) surface waves

Question 60

The fetch of a moving storm system ________ on the side of the storm where the wind is blowing in the ________ direction as the storm is moving.

A) decreases; same
B) decreases; opposite
C) increases; same
D) increases; opposite
E) Both decreases; opposite and increases; same are correct

Question 61

A shallow-water wave has an L of 7 m. At which one of the following heights would it break?

A) 0.1 m
B) 0.4 m
C) 0.7 m
D) 0.9 m
E) 1.1 m

Question 62

A long wave with a period of about 15 minutes will travel across the oceans at a speed of approximately ________.

A) 2 m/sec
B) 20 m/sec
C) 200 m/sec
D) 2 km/sec
E) 20 km/sec

Question 63

A deep-water wave is traveling with a speed of 13 m/s. Its wavelength is ________.

A) 130 m
B) 108 m
C) 13 m
D) 8.3 m
E) 1.3 m

Question 64

Which of the following features of a wave may change during its existence?

A) Height and speed
B) Period
C) Speed
D) Height
E) Wavelength

Question 65

A deep-water wave is traveling with a speed of 13 m/s. Its period is ________.

A) 1.2 seconds
B) 1.3 seconds
C) 8.3 seconds
D) 13 seconds
E) None of these is correct.

Question 66

Wave refraction results in ________.

A) wave energy concentrating in bays
B) wave energy decreasing in bays
C) wave energy focusing on headlands
D) wave energy concentrating in bays and wave energy focusing on headlands
E) wave energy decreasing in bays and wave energy focusing on headlands

Question 67

The speed of shallow water waves is controlled by the ________.

A) height
B) steepness
C) celerity
D) wavelength
E) water depth

Question 68

The speed of a shallow-water wave at a depth of 5 m is ________.

A) 0.2 m/s
B) 0.4 m/s
C) 0.5 m/s
D) 7 m/s
E) 7.8 m/s

Question 69

If the wave height of 1500 waves is recorded, significant wave height will be the average of the highest ________ waves.

A) 15
B) 150
C) 300
D) 500
E) 750

Question 70

Which of the following relates wave height (H) and wave amplitude (A)?

A) H = A/3
B) H = A/2
C) H = A
D) H = 2A
E) H = A²

Question 71

A small island in the open ocean is receiving swell coming from the southeast. Yet, waves break all around its shores, not just the ones facing southeast. The process responsible for this phenomenon is ________.

A) refraction
B) erosion
C) reflection
D) diffraction
E) isostasy

Question 72

A typical wavelength of a tsunami is ________.

A) 1 to 2 m
B) 10 to 20 m
C) 100 to 200 m
D) 100 to 200 km
E) 1000 to 2000 km

Question 73

A wave breaks when ________.

A) h/L = 1/7
B) L/h = 1/7
C) h = 3 m
D) L = 3 m
E) L/h = 3/7

Question 74

A wave period that is representative of a tsunami wave is ________.

A) 5 seconds
B) 10 seconds
C) 15 seconds
D) 1 minutes
E) 20 minutes

Question 75

A water wave reaches an unstable breaking point when the steepness ratio, H/L, reaches ________.

A) 1:10
B) 1:8
C) 1:7
D) 1:5
E) 1:2

Question 76

The correct order of these wave types from fastest (highest) to slowest wave speeds is ________.

A) wind waves - Tsunami - Tides
B) wind waves - Tides - Tsunami
C) tides - Wind waves - Tsunami
D) tides -Tsunami - Wind waves
E) tsunami - Wind waves - Tides

Question 77

As a wave moves to shallower water it stops being a deep-water wave when the depth equals (where L = wavelength) ________.

A) L/0.2
B) L/2
C) L/20
D) L/200
E) L/g