Here's a minorly important circle fact that I find a lot of students don't know: when a wheel is rolling—without slipping—it makes travels a distance of one circumference each time it makes one complete turn. The SAT doesn't test this often, but it's certainly in the realm of testable concepts.
Does that make sense?
It does? OK, cool. Then let's try a tricky question together:
- In the figure above, a wheel with center B and a radius of 12 cm is resting on a flat surface. A diameter is painted on the wheel. If the wheel begins to rotate in a clockwise direction and rolls along the surface without slipping, how far will B travel before the painted diameter is perpendicular to the surface for the first time?
Awesome question, right? I know.