Mechanical Advantage: If a machine is so designed that a smaller effort E is needed to overcome a larger resistive force L. then such a machine is said to have a mechanical advantage.

The mechanical advantage of a machine is defined as the ratio of the load moved by the machine to the effort applied on the machine for this purpose, ie.

Mechanical Advantage = Load/Effort

Velocity Ratio: The velocity ratio of a machine is thus given by the ratio of the distance through which the point of application of the effort moves to the distance through which the point of application of the load moves in the same interval of time. Thus,

Velocity ratio = (Distance moved by the effort)/(Distance moved by the road)

Efficiency: It is the ratio of output to input. In a simple mechanism, it is also defined as the ratio of mechanical advantage to the velocity ratio.

η = (Mechanical Advantage)/(Voltage Ratio)

In an ideal machine, efficiency is 100% or unity so the mechanical advantage is equal to the velocity ratio.