SIMPLE MACHINES: THE LEVER BY: TINA AND LYNETTE

Try pulling a really stubborn weed out of the ground. You know a deep, persistent weed that seems to have taken over your flowerbed. Using just your bare hands, it might be difficult or even painful. With a tool, like a hand shovel, however, you should win the battle. Any tool that pries something loose is a lever!!!!

A lever is an arm that "pivots" (or turns) against a "fulcrum" (or point). Think of the claw end of a hammer that you use to pry nails loose. It's a lever! It's a curved arm that rests against a point on a surface. As you rotate the curved arm, it pries the nail loose from the surface.

The picture displayed shows a lever. The lever is a simple machine made with a bar free to move about a fixed point called a fulcrum. The lever consists of three parts. The fulcrum (see smiling triangle), load (see smiling box) and a rod (see brown plank). Levers are classified into three classes. The First Class Lever, Second Class Lever and the Third Class lever. The only difference between them is the location of the fulcrum.

Levers help you move items that are very heavy. In the First Class lever the fulcrum is located in the middle. The load is on one end and the force is on the other. (crowbar)

Second Class the fulcrum is on the end, the resistance force, the load, is in the middle, and the effort is at the other end. (wheelbarrow)

The Third Class fulcrum is on the end of one side, the effort force is in the middle, and the resistance force, the load, is at the the top. (baseball bat or fishing pole)

Levers are easy to spot because they help us in our lives…. Some examples are: –see-saw, –claw hammer - scissors –crow bar - pliers –bottle opener - bottle opener –Piano keys - nut crackers –car jacks - tongs –Door hinges

References nes/Levers.shtml machines mpmach.htm edtech.kennesaw.edu/web/simmach.html