|Inclined Plane | Wedge | Screw | Lever | Wheel and Axle | Pulley||Back to Step 1|
The second way of using a wheel is like a lever in the round. A door knob or a faucet on a sink are really round levers, and the "fulcrum" is in the middle where the axle turns. Imagine if a door knob was replaced with a little rod. It would be much harder to open the door! Once again, there's a trade-off: The larger the diameter of the wheel, the less effort you need to turn it, but you have to move the wheel a greater distance to get the same work done.