EOSC 114 Midterm 3 - Waves exam with
complete solutions
1) Explain how waves move matter and energy
Normal Waves - ANSWER- Waves transport energy. There are Body (P and S)
waves or surface (Rayleigh and love) waves. They are various speeds.
Medium/matter (rock or ground) moves as waves pass, but there is ZERO NET
MOTION
1) Explain how waves move matter and energy
Ocean Waves - ANSWER- Transport energy through water (medium/matter).
Similar to surface Rayleigh waves, move at various speeds. Water moves as
waves pass, but net motion is ZERO. Generated by wind and other geological
events
2) Identify key properties of waves
Wave Anatomy: Shape - ANSWER- Crest = highest point
Trough = lowest point
Wavelength = distance for one full cycle (crest-to-crest, or trough-to-trough)
Wave height = vertical distance from crest to trough
Amplitude = one half the height (H/2)
Steepness = Height divided by wavelength (H/L)
What is a sea? - ANSWER- Jumble of waves of various lengths and directions
What is a swell? - ANSWER- Series of waves generated at a distance, well sorted
As a wave approaches shore, its L (wavelength) decreases and its H (height)
increases, and steepness does what? - ANSWER- Increases
, 2) Identify key properties of waves
Wave Anatomy: Motion - ANSWER- Period (T) = seconds per cycle, time it takes
for one wavelength to pass a point
Frequency (f) = cycles per second, number of waves per time period (Hz = hertz)
Celerity (s) = also known as speed, distance per time period (m/s)
How do particles move as a wave passes? - ANSWER- Backward than upward as
trough passes
Forward than downward as crest passes
Circular motion (orbits), orbital motion decreases with depth
Energy passes through water, NO NET MOVEMENT (seagull stays in place)
In open ocean, water remains in place and is the medium for the wave energy to
travel through
2) Identify key properties of waves
Orbital motion with depth - ANSWER- Wave orbits are largest at the surface
Orbits decrease with depth
Orbits disappear below: d> 1/2L
At d>1/2 there's essentially no movement occuring
3) Use these properties to determine wave speed and behavior in either shallow
or deep water.
Deep Water Wave - ANSWER- D = ocean depth
D >= L/2
Waves do not "feel" ocean floor
Ocean is deeper than (L/2)
Celerity depends on wavelength (L)
Speed can be expressed as (C = L/T)
C = 1.56T
3) Use these properties to determine wave speed and behavior in either shallow
or deep water.
Shallow Water Wave - ANSWER- D <= L/20
Waves "feel" ocean floor
C = sqrt(g x d)
C = 3.1sqrt(d)
complete solutions
1) Explain how waves move matter and energy
Normal Waves - ANSWER- Waves transport energy. There are Body (P and S)
waves or surface (Rayleigh and love) waves. They are various speeds.
Medium/matter (rock or ground) moves as waves pass, but there is ZERO NET
MOTION
1) Explain how waves move matter and energy
Ocean Waves - ANSWER- Transport energy through water (medium/matter).
Similar to surface Rayleigh waves, move at various speeds. Water moves as
waves pass, but net motion is ZERO. Generated by wind and other geological
events
2) Identify key properties of waves
Wave Anatomy: Shape - ANSWER- Crest = highest point
Trough = lowest point
Wavelength = distance for one full cycle (crest-to-crest, or trough-to-trough)
Wave height = vertical distance from crest to trough
Amplitude = one half the height (H/2)
Steepness = Height divided by wavelength (H/L)
What is a sea? - ANSWER- Jumble of waves of various lengths and directions
What is a swell? - ANSWER- Series of waves generated at a distance, well sorted
As a wave approaches shore, its L (wavelength) decreases and its H (height)
increases, and steepness does what? - ANSWER- Increases
, 2) Identify key properties of waves
Wave Anatomy: Motion - ANSWER- Period (T) = seconds per cycle, time it takes
for one wavelength to pass a point
Frequency (f) = cycles per second, number of waves per time period (Hz = hertz)
Celerity (s) = also known as speed, distance per time period (m/s)
How do particles move as a wave passes? - ANSWER- Backward than upward as
trough passes
Forward than downward as crest passes
Circular motion (orbits), orbital motion decreases with depth
Energy passes through water, NO NET MOVEMENT (seagull stays in place)
In open ocean, water remains in place and is the medium for the wave energy to
travel through
2) Identify key properties of waves
Orbital motion with depth - ANSWER- Wave orbits are largest at the surface
Orbits decrease with depth
Orbits disappear below: d> 1/2L
At d>1/2 there's essentially no movement occuring
3) Use these properties to determine wave speed and behavior in either shallow
or deep water.
Deep Water Wave - ANSWER- D = ocean depth
D >= L/2
Waves do not "feel" ocean floor
Ocean is deeper than (L/2)
Celerity depends on wavelength (L)
Speed can be expressed as (C = L/T)
C = 1.56T
3) Use these properties to determine wave speed and behavior in either shallow
or deep water.
Shallow Water Wave - ANSWER- D <= L/20
Waves "feel" ocean floor
C = sqrt(g x d)
C = 3.1sqrt(d)
