How is efficiency defined in mechanical terms?

Efficiency in mechanical terms is defined as the ratio of output work to input work, expressed as a percentage. This definition captures the essence of how well a machine converts input energy into useful work. A machine is considered efficient if a large proportion of the energy it consumes is transformed into work that accomplishes its intended purpose, rather than being lost to factors such as friction or heat.

For example, if a machine does 80 joules of useful work from 100 joules of energy input, its efficiency would be calculated as (80/100) × 100%, resulting in an efficiency of 80%. This measure is crucial in comparing different machines or processes, as a higher efficiency indicates a more effective use of energy. Understanding this concept helps in optimizing machines and improving their performance in various applications.