机械效率是力学中一个重要概念,在初二物理《力》一章中处于核心位置,也是中考试题热点之一。能否有效地用好机械效率解题,关键在于对机械效率、有用功、总力、额外功及相关知识的理解。因此,运用机械效率解决问题时,需做到“五要”1正确理解机械效率的概念有用功跟总功的比值 Mechanical efficiency is an important concept in mechanics. It is at the core position in the second chapter of Physics’s “force” and is also one of the hot topics in the middle exam. The key to effective use of mechanical efficiency is the understanding of mechanical efficiency, useful work, total force, extra work, and related knowledge. Therefore, when using mechanical efficiency to solve problems, it is necessary to achieve “five priorities” 1 to correctly understand the concept of mechanical efficiency, the ratio of useful work to total work.