Something to Show Your Algebra Classes

I actually found a reference to variation that isn't in a text book. The Wired Science blog had a post on high-altitude wind generation (pretty interesting in its own right). They describe the relationship between wind speed and power generated like this...

Wind’s power — energy which can be used to do work like spinning magnets to generate electricity — varies with the cube of its speed.

I wonder how many of the students I tortured with variation would remember what it means if they read this article? Those are the questions that keep a math teacher up at night. BTW, if you're teaching variation. I've always found that students like knowing the world's most famous equation e=mc^2 is a direct variation equation.