我们知道,应用机械能守恒定律研究问题不必考虑两个状态之间的过程细节,所以显得很方便、简单。但在应用之前,要先判断系统的机械能是否守恒。如何判断,成了学生的一大难题,就此,本人谈点看法。在教材中,依据机械能守恒定律的内容“在只有重力或弹力做功的物体系统内,动能与势能可以相互转化,而总的机械能保持不 We know that applying the law of conservation of mechanical energy does not have to account for the details of the process between two states, so it is easy and simple. However, before the application, we must first determine whether the conservation of mechanical energy system. How to judge, has become a major problem for students, in this regard, I talk about the point of view. In textbooks, according to the law of conservation of mechanical energy, ”kinetic energy and potential energy can be transformed into each other in an object system that uses only gravity or elasticity, and the total mechanical energy remains unchanged