In the previous section, you looked at one wave property, oscillatory motion. In this section, you will look at another wave property, wave propagation.

Watch the clip below demonstrating wave motion on a special machine. As you watch the clip, record your observations about where the wave starts and how it moves from the starting point in your notes.

Source: Wave Machine Operation, bcitphysics, YouTube

You may have noticed that the wave started at one point of the machine and then initially moved away from that point.

Let’s watch another clip that will better assist you with an understanding of what is happening with the wave machine. You only need to watch the first 23 seconds of the video. Do not worry about the formulas that are mentioned in the video.

Source: Wave Propagation, Frank McCulley, YouTube

Considering the motion of the wave machine and information from the previous video clip, what can be said about wave motion and propagation?

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Propagation is the way in which waves travel away from the source of a disturbance.

Now that you understand wave property of propagation, let’s look at how waves propagate in different mediums. In this case, look at the medium of air with sound waves and the medium of water.

Answer the questions below as you watch the following video clip.

Source: Part3-Wave propagation-sound&waterfinal.wmv, iscaleon, YouTube

1. Describe how sound waves move through air.

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As sound waves propagate through air, air particles move slightly left and right.

2. Why do the air particles stay in the same location?

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Air particles stay in the same location because interaction forces join them.

3. How is propagation in water waves similar to propagation in sound waves?

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The wave moves through the medium but does not greatly impact the particles in the medium.

4. How is propagation in water waves different from propagation in sound waves?

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Sound waves oscillate from side to side; water waves have different oscillation patterns.

Based upon the information you have seen in this section, how would you describe wave propagation?

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Wave propagation is the movement of a wave away from the source of the disturbance.