January 21 lecture

Question 1

What are Waves?

Answer 1

Waves are energy transmitted through matter

Question 2

Does the medium move as energy passes through it?

Answer 2

No, the medium dose not move as energy passes through it but constituent particles oscillate in place as the energy passes through them

Question 3

How do waves move through matter?

Answer 3

In the the 3d

Question 4

What are progressive waves?

Answer 4

Waves where the wave from can be seen travelling through the medium

Question 5

What two forces cause waves?

Answer 5

Disturbing forces

restoring forces

Question 6

What is a disturbing force?

Answer 6

A disturbing force that modifies a ‘undisturbed’ medium to create the wave

Question 7

What are the most common disturbing forces?

Answer 7

Most common such force is the wind that blows over the surface and transfers energy to the ocean

Question 8

What are restoring forces?

Answer 8

A restoring force that tends to bring a system to its undisturbed state

Question 9

What is the restoring force for a liquid

Answer 9

Gravity

Question 10

What is the point of highest elevation on a wave?

Answer 10

The crest

Question 11

What is the depression between each pair of crests called?

Answer 11

the trough

Question 12

What is the distance between each successive pair of crests or troughs called?

Answer 12

The wavelength

Question 13

What represents wavelength

Answer 13

λ (Lambda)

Question 14

What is the vertical distance between crests and trough?

Answer 14

Height, represented as H

Question 15

What is the vertical distance between crests and trough and the MEAN water level?

Answer 15

The amplitude. (H/2)

Question 16

What is a wave period? (T)

Answer 16

It is the time it takes fro a wave to move a distance equal to one wavelength.

or

The time between the arrival of two successive crests or troughs at a given location.

Question 17

What is a waves frequency?

Answer 17

the number of crest or troughs that pass a point in a fixed unit of time. (f)

Question 18

How are period and frequency related?

Answer 18

T = 1/f

Question 19

What is wave speed (C)?

Answer 19

It is related to the speed of ‘movement’ of a wave crest.

Question 20

What is the equation for wave speed?

Answer 20

C = λ/T

Question 21

What is Wave Steepness?

Answer 21

The ratio of the wave height to the wavelength (H/λ)

Question 22

When waves move across the ocean unbroken is there any net movement of the water?

Answer 22

There is no net forward motion of the water itself, only energy associated with the wave from within the wave moves.

Question 23

What is Stokes Drift?

Answer 23

When the forward speed of the crest is faster than the backwards speed at the base of the trough due to particle speed decreasing with depth.

So particles will move slightly farther forward at the crest than they move back at the trough

Question 24

What 5 things create waves?

Answer 24

1. ) interactions of wind with the oceans surface
2. ) Impacts on the ocean
3. )Tidal interactions
4. ) Passage of vessel or marine mammals
5. ) Density interfaces within the ocean or on the surface ( internal waves )

Question 25

What happens to wave shape over time?

Answer 25

They go from more regular Sinuoidal form to the trochoidal shape

Question 26

What is a Sinusoidal wave?

Answer 26

a regular rounded wave shape

Question 27

What is a trochoidal wave shape?

Answer 27

pointed crests and rounded troughs

Question 28

When waves get too steep they will break, at what height to wavelength ratio will this happen?

Answer 28

1:7 of HIght:Wavelengths

Question 29

Winds never blow uniformly over the ocean, how does this affect wave formation? what is the result called?

Answer 29

We get waves of many heights, wavelengths, periods, directions. This is called the SEA

Question 30

What is a swell?

Answer 30

It is where waves are generally smooth, from the same direction and have the same wavelength

Question 31

What does wave height depend on?

Answer 31

Wind speed, wind fetch, wind duration and water depth.

Question 32

In the open ocean what travels faster Longer waves or Shorter waves

Answer 32

Longer waves travel faster

Question 33

What is wave dispersion?

Answer 33

When longer waves move faster than shorter waves in the ocean.