How to build moveable parts. 6 simple mechanisms. Inclined Plane Lever Pulley Screw Wedge Wheel and Axle. Pulley.
The lever has two important parts. The lever itself and the fulcrum. The placement of the fulcrum determines how far the levered object will move, and how much force is required to move it.
If a weight was resting on a lever a person could lift the weight by pressing on the lever on the other side. The farther away from the fulcrum that person pressed, the less force that person would need to apply. In order to lift the weight the same distance, the force would have to be applied over a longer distance. In science, we call how much effort it takes to move something a certain distance "work." With a lever, you always do the same amount of work no matter how long your lever is. But if you are moving the lever further, then you don't have to push as hard to do the same amount of work.