EN: Energy is the ability to cause change in a system or do work. - Energy appears in different forms (mechanical, thermal, chemical, electrical, radiant, etc.). - Energy can be transferred between a system and its surroundings, or transformed from one form to another. - The SI unit of energy is the joule (J).

中文：能量是使系统发生变化或对物体做功的能力。 - 能量有多种形式（机械、热、化学、电、辐射等）。 - 能量既可以在系统与环境之间传递，也可以在不同形式之间转化。 - 能量的国际单位是焦耳（J）。