How wheels are used in doing work. Wheels are so commonly used in machines that when most of us think of machines and machinery, we also think of wheels. Like the lever, they may be used to gain force at the expense of distance or speed, or may be used to obtain speed or distance [...]

1. Plan and carry out a series of demonstrations to illustrate the various uses of levers.
2. Construct a windlass and demonstrate its use to the class.

3. Construct a set of cogwheels by which power is gained at the expense of speed.
.4. Construct a set of cogwheels by which speed is gained [...]