Lately in physics we have been talking about waves and the different types of waves. We learned about a transverse wave which are perpendicular to the direction of wave travel. Besides transverse waves we learned about a longitudinal wave which are parallel to the direction of wave travel. Another type of wave is a mechanical wave, for a mechanical wave to work it must have a medium. Sound is a type of mechanical waves they need a medium for them to work. Which is why in space you can not hear sound because there are no mediums for the sound wave to travel though. When a wave enters a new medium its frequency stays the same. The last type of wave is an electromagnetic wave, and it is different from a mechanical wave because it does not need a medium to travel through. A single vibratory disturbance in a wave is called a pulse. The amplitude is the height of from when the wave is at rest to the crest.