What formula is used to calculate efficiency?

The formula for calculating efficiency is based on the ratio of useful output work to the total input work, expressed as a percentage. This means that to determine how effectively a machine or system converts input energy into useful output energy, one uses the output work in the numerator and the input work in the denominator.

The correct formula, which is efficiency equals (output work divided by input work) multiplied by 100, allows you to understand the performance of the machine or system. A higher efficiency percentage indicates that a greater portion of the input work is being converted into useful work rather than being lost to friction, heat, or other inefficiencies.

This concept is crucial in fields such as engineering and physics, as it helps in assessing and improving the performance of machines. The other equations mentioned either use incorrect variables or describe different concepts related to power and work, rather than the fundamental definition of efficiency.