Simple machine: lever

A simple machine is a mechanical device that changes the direction or magnitude of a force. Classical and Renaissance scientists defined six different ones. A lever (here by Linda Hamilton) is a rigid rod that pivots on a point called the fulcrum. In a class 1 lever, when a downward force is applied on one side of the fulcrum, an upward force results on the opposite side.



It also makes a difference how far the point of force application is from the fulcrum, as the actual term to be considered is torque, defined as the amount of force times the distance. The longer the lever, the greater torque can be produced, so that very large objects can be moved, as shown here by Ringleader. Archimedes supposedly said he could lift the earth if he were given a long enough beam and a place to set the fulcrum.