O_TEXTBLOCK_TEXT The teeth of one gear fit into the notches of the second gear, which makes them turn. When two gears are used, the drive gear (the one with the turning power) turns the other gear in the opposite direction. When three gears are used, the second gear moves in the opposite direction of the drive gear, and the third gear moves in the same direction as the drive gear.
E_QUEST1 For each turn of the large gear on your bicycle, how many times does the small gear turn?
E_QUEST2 What happens when you switch to a lower gear?
E_QUEST3 How does a can opener work?
D_TEXTBLOCK_TEXT Wheels with teeth and notches in them are called gears. Gears can be used to change the direction of turning <HL Topic=Motion.tpc>MOTION</HL>. They are sometimes used in <HL Topic=Wheel.tpc>WHEEL AND AXLE</HL> <HL Topic=Machine.tpc>MACHINES</HL>.