The Lever

The lever may have been the first machine man learned to use. Cavemen almost certainly knew how to move a heavy rock with the help of a strong pole. All they had to do was to force one end of the pole under the rock and put a smaller rock on the ground under the pole near the same end. By pushing down on the other end of the pole, they could raise the rock. 

About 4000 years ago, the Great Pyramid was built in Egypt. It took about 30 years to build. There is no record of how it was built, but the lever may have been the principal machine used. Great teams of workmen may have levered the massive blocks of limestone out of quarries (workweek), dragged them to the site of construction, and then used inclined planes built of sand to raise them up onto the pyramid. Each block has a mass of about. Today, levers are more popular than ever. They are used in many household tools, such as scissors, pliers, the crowbar, and the claw hammer. 

Simple Machines

There are just six kinds of simple machines. Each kind has many uses. Big machines are merely many simple machines put together. The six kinds of simple machines are the lever, the pulley, the wheel and axle, the inclined plane, the wedge, and the screw.