Gears

For background, we started our unit with the history of the wheel using a junior encyclopedia (Grandes Inventions de la prehistorique a 1900, Editions Tout Connaitre"

To learn about gears in motion, we read How Stuff Works, which has dynamic diagrams.

To experiment with gears, we bought a supplementary kit for Knex called Intro to Simple Machines: Gears. (This kit can be used on its own.)

General observations:

- round and flat

- have teeth

-a whole in the middle for the axis

-come in many different sizes

We observed that gears:

- change the speed of rotation

- change the direction of rotation

- move the rotation to a new axis

- synchronize rotation of axes

-gears don't move in the same, they alternate direction

Why gears have teeth:

- to grip on to each other

- to stay synchronized

- compensates for gears that are almost identical in size (number of teeth is more important than the precise diameter)

Vocabulary: gear, gear ratio, torque, axis, speed, direction, diameter, teeth, gear trains, rpm, revolutions per minute, threaded shaft, worm gear, planetary gears