ubiSci Ubiquitous Science Western Reserve Public Media

Waves and Speed

When you think of waves, you probably think of the ocean’s waves that hit the shore and are used for surfing. There are other waves that surround you all the time. Light waves allow you to see the world around you. Sound waves bring voices and music to your ears. Heat waves warm you.

So what is a wave? If you throw a pebble into water, a series of collisions between the molecules causes the energy to be carried through the water. You see the energy caused by the pebble move as a wave. A wave is a disturbance that transfers energy through matter or space.


Types of Waves

There are two types of waves as determined by the way the energy disturbs the molecules. One is called a transverse wave. If you tie one end of a rope to a chair, hold the other end and move it up and down, you create a transverse wave in the rope. The fibers that make up the rope move up and down. The highest point of the wave is called the crest and the lowest point is called the trough.


You can see transverse waves in flags or tall grass when the wind blows. What medium would they be traveling though?

The second type of wave is called a longitudinal wave. The action of this type of wave can be seen in a spring or a Slinky toy. If you compress — or push together — the coils in one part of the spring, the potential energy becomes kinetic energy that moves through the spring like a wave. When the coils are put together, this is called compression.

When the waves spread apart in another part of the spring, this is called rarefaction.

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