Heavy Lifting

The ancient Greek scientist Archimedes was the first person to correctly describe a lever mathematically. He supposedly said, "Give me a place to stand, and I shall move the earth with a lever." Well, that's an exaggeration because it would have to be one pretty big lever!

However, levers can be used to move heavy objects or to make a distant object move faster or farther. Here are just a few devices that use the principle of the lever to work: scissors, seesaws, tweezers, wheelbarrows, nutcrackers, the human jaw, fishing rods, and catapults. These things may not seem to have much in common, but you'll learn that they do.

There are two main parts to a lever. First, there is a bar or a board. This rests on a turning point called the fulcrum. The object to be lifted or moved is the load, and the work that you (or something else) does is called the effort.

There are three classes of levers: first, second, and third (OK, the names aren't very original!). The differences among them are the positions of the fulcrum, load, and effort. We'll look at each of them in turn, and you'll see how each of them can make your life easier!