How is the effectiveness of a machine in performing work known?

The effectiveness of a machine in performing work is known as efficiency. Efficiency is a measure of how well a machine converts the input energy or work into useful output energy or work. It is typically expressed as a percentage, calculated by taking the ratio of the useful work output to the total work input and multiplying by 100. High efficiency indicates that a machine wastes little energy and performs its intended task effectively, while low efficiency suggests that a significant amount of energy is lost, often due to factors like friction or heat loss.

In the context of machines, understanding efficiency is crucial because it helps in assessing the performance of the machine in real-world applications. It directly influences considerations such as energy consumption, operational costs, and overall sustainability. Other concepts like performance may relate to how a machine operates under certain conditions, power refers to the rate at which work is performed, and output typically relates to the amount of work or energy produced, but these do not specifically measure the effectiveness of a machine in the same way that efficiency does.