How is the mechanical efficiency of a machine usually expressed?
Group of answer choices

as a fraction

as a percentage

as inches or feet

as one of three classes

As a percentage

Explanation:

The mechanical efficiency of a machine is the percentage of energy in input to the machine that is converted into useful work.

Mathematically, the efficiency of a machine is given by:

where:

W is the useful work in output from the machine

E is the energy in input to the machine

For example, a machine with 80% efficiency means that it converts 80% of the input energy into work.

A machine can never be 100% efficient, since part of the input energy is wasted due to the presence of frictional forces.

So, the efficiency of a machine is expressed as a percentage.

that would be because of both gravity and friction. so     c