Ideal machine

From ArticleWorld

In the study of mechanics, a theoretical ideal machine is one which possesses an actual mechanical advantage which is equal to its ideal mechanical advantage. An ideal machine is free from frictional forces and has a mechanical efficiency of 100 per cent.

Use of the term 'mechanical advantage'

The mechanical advantage of a machine is the ratio of the force that performs useful work to the input force. The term 'mechanical advantage' in the study and application of mechanics is in essence a measure of the force-amplifying effectiveness of a simple machine, such as a lever, an inclined plane, a pulley or a wheel.

Mechanical advantage is more important when considering the operation of simple machines, such as levers or screws. When it comes to the study of complex machines, however, the term loses its importance because complicated machines cannot be studied simply by looking at ratios of input and output forces.

Relationship between values of ideal and actual mechanical advantage

The theoretical or ideal mechanical advantage of a machine can be calculated as the ratio of the output force produced by the machine to the input force that is applied to the machine. This value is calculated without taking into consideration the effect of frictional forces that are associated with the system.

However, in practice, there always is frictional force associated with any mechanical system, with the result that the actual mechanical advantage will be less than the theoretical value. The value by which the actual mechanical advantage differs from the ideal is determined by the amount of frictional force that is present. Frictional forces account for most of the energy losses during the operation of machines.

In an ideal machine, the theoretical mechanical advantage and the actual mechanical advantage values are equal. The mechanical efficiency, which is the ratio of the actual mechanical advantage to the ideal mechanical advantage, is equal to 100 per cent in the case of ideal machines.