5.25 Surface Wave
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 theFigure5.50 and at this URL: http://www.youtube.com/watch?v=7yPTa8qi5X8
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/5035FIGURE 5.50
Why Waves Break
In deep water, particles of water just move in circles. They don’t 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 theFigure5.51.
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.
Summary
- A surface wave is a wave that travels along the surface of a medium. Ocean waves are the best-known examples
of surface waves. - In a surface wave, particles of the medium move up and down as well as back and forth in an overall circular
motion. The particles don’t actually move closer to shore as the waves pass through. - In shallow water close to shore, waves start to drag on the bottom of the water. The bottoms—but not the
tops—of the wave slow down because of friction. This causes the waves to steepen until they break and fall
over, carrying water onto the shore as surf.