What is the ratio of output work to input work called?

The term that defines the ratio of output work to input work is known as efficiency. Efficiency is a measure of how effectively a machine converts input energy into useful work. It is usually expressed as a percentage, calculated by dividing the useful output work by the total input work, and then multiplying by 100.

For example, if a machine uses 100 units of energy and produces 80 units of useful work, its efficiency would be 80%. This concept is fundamental in engineering and physics, as it allows engineers to assess how well a system is performing relative to its potential.

The other terms do have specific meanings within mechanical systems but do not refer to the ratio of work in the same context. Mechanical advantage relates to the factor by which a mechanism multiplies the force applied, the velocity ratio refers to the ratio of the distance moved by the effort to the distance moved by the load, and power is a measure of the rate at which work is done. Each of these plays a role in understanding mechanical systems but efficiency remains the key term for output work in relation to input work.