Gear Race

Different sized gears can be used to magnify force or distance (speed).

How it works

Combine small, medium and large gears and turn a handle to race a toy camel and a toy horse along a track.

Things to try or ask around the exhibit

• If you want the toy camel to win the race, what's the best combination of gears to use?
• How many teeth does each gear contain? Do you recognise a pattern in the numbers of teeth?
• What's the difference between the way a small gear spins compared to a large gear?
• What do you notice when you connect a mixture of the smallest and the largest gears?
• If a medium-sized gear pushes on the smallest gear, how fast with the small gear spin?

Background

Gears are wheels with bumpy edges or teeth that fit together. Gear teeth push on each other so they can turn and do work.

Large gears have more teeth than small gears. In this exhibit, the smallest gears have 30 teeth, the medium-sized gears have 60 teeth and the largest gears have 90 teeth. The largest gears (90 teeth) have three times more teeth than the smallest gears (30 teeth), so we say their gear ratio is 3:1.

When the teeth on the largest gear push against teeth on the smallest gear, the small gear spins around three times faster, while the larger gear spins more slowly than the small gear, but with greater force. This is called movement magnification.

Finding the science in your world

Gears are found in many appliances around the house, such as wine bottle openers, analogue clocks, guitar tuning keys and food processors.

In vehicles such as cars, gears are a vital part of steering shafts and engines. Without them, a car wouldn't be able to turn and an engine wouldn't be able to shift 'gears' and engine power.