Basic Machines

Machines are mechanical devices which are designed such that available sources of energy, force or effort can be used to perform a useful task or to do work. Some Basic Machines simply enable effort to be applied in a more convenient direction, but more often they are used to increase the load that can be moved or amplify the distance travelled.

Lever	Levers are described in three ‘classes’ as determined by the relative positions of the load, fulcrum and effort. Levers are often used to move heavy loads, as with the Class 1 Lever shown, but if used in reverse, as it were, and the heavy boulder becomes the applied force, then we have the basis of a Trebuchet type seige weapon making use of the amplification of movement the lever can provide. The extent to which a Lever can increase effort is calculated as its Mechanical Advantage and the degree to which it amplifies movement is calculated as its Velocity Ratio
Pulley	Pulleys can be used speed up or slow down rotating shafts or, as in the example shown, simply to change the line of effort to a more convenient direction.