How is efficiency often measured in mechanical systems?

Efficiency in mechanical systems is typically measured by the ratio of useful output energy to the total input energy. This approach illustrates how well a system converts the energy put into it into useful work. When you calculate efficiency using the formula of output energy divided by input energy, the result is expressed as a percentage. This percentage indicates how much of the input energy is effectively utilized compared to how much is wasted.

For example, if a machine consumes 100 units of energy and produces 80 units of useful work, its efficiency would be 80% (80 units of output energy divided by 100 units of input energy). This metric is crucial in evaluating the performance of machines and engines, as higher efficiency means lower energy wastage and better resource utilization.

In contrast, the other methods for determining efficiency do not accurately reflect the overall performance of mechanical systems in terms of energy usage and waste.