Have you ever looked at the inside of a pendulum-style clock or a wind-up watch? Or have you ever looked at a 10 or 24-speed bike? There are different sized wheels with “teeth” (or bumps and ridges) on them. When one wheel turns, the teeth mesh with the teeth on another wheel and cause the second wheel to turn also. These toothed wheels are called gears. Gears can be of all different sizes and are specifically created in order to get just the right amount of work and just the right amount of turning to happen from using just the right amount of force.

Gears are connected together in various ways to transmit motion and force. Two connected gears of different sizes will cause one of the gears to turn faster or slower than the other. One gear will also move the force in a different direction than the other.