On the previous page we talked about how radio and light are both manifestations of the same thing: an electromagnetic wave. Here we will talk a bit more about waves. Mechanical waves are the waves that are most familiair and understandable to us. Unlike electromagnetic waves mechanical waves need a medium to travel through, like water, air, or solid materials.
Waves in water
Go to a pond near you, grab a rock and throw it in the water and what you will see are waves. You probably know what a wave looks like, but I couldn't resist demonstrating it with a silly animation.
What is important to note is that a wave, either mechanical of electromagnetic, is traveling energy. The wave in the animation above is made of energy, not of water. The energy of the wave is traveling through the water (the medium), because the water particles are bumping in to each other, passing on the energy of the wave.
That is why the fish in the animation only moves slightly when the wave passes. It doesn't travel with the wave, at least not very much, because the water particles don't move very much. They just pass on energy.
The waves you get when you throw a rock in the pond or when you clap your hands (sound waves) are both mechanical waves.
A mechanical wave transports energy through a medium. In the pond example, the medium is obviously water. Sound waves travel through water, through air and to some extent through solid materials.
On the next page you will learn about frequency and wavelength, two properties common to both mechanical and electromagnetic waves.