# surface wave

## waves on the surface

A surface wave is a wave that travels along the surface of a medium. The medium is the matter through which the wave travels. Ocean waves are the best-known examples of surface waves. They travel on the surface of the water between the ocean and the air. Q: What do you think causes ocean waves? A: Most ocean waves are caused by wind blowing across the water. Moving air molecules transfer some of their energy to molecules of ocean water. The energy travels across the surface of the water in waves. The stronger the winds are blowing, the larger the waves are and the more energy they have.

## how the medium moves

A surface wave is a combination of a transverse wave and a longitudinal wave. A transverse wave is a wave in which particles of the medium move up and down perpendicular to the direction of the wave. A longitudinal wave is a wave in which particles of the medium move parallel to the direction of the wave. In a surface wave, particles of the medium move up and down as well as back and forth. This gives them an overall circular motion. You can see how the particles move in the Figure 1.1. Click image to the left or use the URL below. URL:

## why waves break

In deep water, particles of water just move in circles. They dont actually move closer to shore with the energy of the waves. However, near the shore where the water is shallow, the waves behave differently. Look at the Figure 1.2. You can see how the waves start to drag on the bottom in shallow water. This creates friction that slows down the bottoms of the waves, while the tops of the waves keep moving at the same speed. The difference in speed causes the waves to get steeper until they topple over and break. The crashing waves carry water onto the shore as surf. Q: In this diagram of a wave breaking near shore, where do you think a surfer would try to catch the wave? A: The surfer would try to catch the wave where it starts to steepen and lean forward toward the shore.

## instructional diagrams

No diagram descriptions associated with this lesson

## questions

a surface wave is one type of mechanical wave.

``````-->  a. true

b. false
``````

an ocean wave is an example of a surface wave.

``````-->  a. true

b. false
``````

in deep water, how do particles of water move when a surface wave passes through them?

``````a) up and down

b) back and forth

c) in an overall circular motion

-->  d) all of the above
``````

why do surface waves break along the shore?

``````-->  a) the waves start to drag on the bottom.

b) the tops of the waves speed up.

c) the waves become less steep.

d) all of the above
``````

the larger a surface wave is, the more energy the wave has.

``````-->  a. true

b. false
``````

an ocean wave carries water all the way across the ocean to the opposite shore.

``````a. true

-->  b. false
``````

## diagram questions

No diagram questions associated with this lesson