Simple machines. A collection of household tools that use simple machine principles. All of those here are based on the lever. The principle of a lever is of mechanical advantage - a force applied at a given distance from a fulcrum (point of rotation) being magnified by being used at a point closer to the fulcrum. The lever-arm corkscrew (centre) also uses a helical screw. The tweezers (upper right) reduce the mechanical force applied, but apply it to a very small surface to grip tiny objects.