This example is about seismic waves.The diagram below shows the path of a wave through a layer of rock. The wave travels with velocity v1, down from the point A to the point B, at an angle q. It then travels along from B to C with velocity v2, and up along CD with velocity v1. The depth of the layer is h1 and the distance from A to D is L.
The time, t, that the wave takes to travel a distance d at a velocity v is given by
How long does the wave take to travel from A to D through the points B and C?
To answer this, we need to work out how far it's going at what speed. We will need to use the trigonometric functions. To find out about these, go into the MathHelp notebook on trigonometry. At the end of the notebook you'll be given the opportunity to see the solution of this problem.