Mechanical devices are used to magnify the applied force (mechanical advantage), to magnify the distance moved, or to change the direction of the applied force. They of course cannot decrease the amount of work (force × distance) necessary to do a job; they only make it more convenient to do it. In many cases, without a machine, the job would be impossible.

There is generally considered to be five distinct simple machines: lever, wedge, wheel and axle, pulley, and screw. The transmission of energy by these simple machines is so basic that people use them with little understanding of the physical principles involved. Most learn their use intuitively, through experience, and consider their application just plain common sense.

The Basics

The history of the origin of simple machines is largely conjectural, but there also exists documentation of the ancient Egyptians using simple machines...