Sound

Hold a finger against your throat and hum. What you feel is the whole of this topic in one sensation: something is shaking, and because it is shaking you can hear it. Every sound that has ever reached you began as a vibration and arrived as a vibration, carried across the room by air that squashes and stretches hundreds or thousands of times a second without ever travelling anywhere itself. Take the air away and the vibration has nothing to ride on, which is why the loudest explosion in space would reach you in complete silence.

This lesson takes that idea and turns it into physics you can calculate with. You will learn why a sound is high or low and why it is quiet or deafening, where the two limits of your own hearing sit, and what happens when a sound wave runs into a wall or squeezes through a doorway. You will learn to turn a clap and a stopwatch into a measurement of the speed of sound, and to run the wave equation both ways for a sound wave you cannot hear. There are only three statements in this topic and every one of them is Core Tier, so whichever tier you are entered for, all of it is yours to know.