17.1 Mechanical Waves
Reading Focus
Key Concepts
What causes mechanical waves?- What are the three main types of mechanical waves?
Vocabulary
mechanical wave
medium
crest
trough
transverse wave
compression
rarefaction
longitudinal wave
surface wave
Reading Strategy
Previewing Copy the web diagram below. Use Figure 2 to complete the diagram. Then use Figures 3 and 4 to make similar diagrams for longitudinal waves and surface waves.
Have you ever gone to a wave pool at an amusement park? You can hear the laughter and screams as wave after wave passes by, giving the people a wild ride. It's obvious that waves are moving through the water, but you may not realize that the screams and laughter are also carried by waves. In this chapter, you will learn about the different kinds of mechanical waves, including sound waves.
What Are Mechanical Waves?
A mechanical wave is a disturbance in matter that carries energy from one place to another. Recall that energy is the ability to do work. In a wave pool, each wave carries energy across the pool. You can see the effects of a wave's energy when the wave lifts people in the water.
Figure 1 In a wave pool, the waves carry energy across the pool.
Mechanical waves require matter to travel through. The material through which a wave travels is called a medium. Solids, liquids, and gases all can act as mediums. In a wave pool, waves travel along the surface of the water. Water is the medium. Waves travel through a rope when you shake one end of it. In that case, the medium is the rope.
A mechanical wave is created when a source of energy causes a vibration to travel through a medium. A vibration is a repeating back-and-forth motion. When you shake a rope, you add energy at one end. The wave that results is a vibration that carries energy along the rope.
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