Simple machines are best described as devices that _______________.
allow a smaller force to move a larger load
A simple machine, such as a lever, pulley, wheel and axle, inclined plane, wedge or screw, is a device that makes work easier by changing the size or direction of the force applied.
Most simple machines give a mechanical advantage (load ÷ effort greater than 1), so a small effort can lift or move a heavy load; for example, a crowbar lifts a heavy stone and an inclined plane lets a heavy box be pushed up instead of lifted. The work is not reduced, but the force needed is smaller because it acts over a longer distance.
Simple machines still need an effort to be applied, so they do not replace all human effort. They do not change the material of the load. Friction is a loss in a machine that lowers its efficiency, so machines are designed to reduce friction, not increase it.
Hence, allow a smaller force to move a larger load.
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