机械能守恒定律和动量守恒定律是高中物理的重点内容,也是高考的热点知识,应用这两个定律解题,只需考虑始末状态,不必涉及中问过程,常给解题带来很多方便;而且有些变力做功的问题,用牛顿第二定律和匀变速运动知识不能解决,但用上述定律来解,却能收到意想不 The law of conservation of mechanical energy and law of conservation of momentum are the key content of high school physics, and it is also a hot topic of college entrance examination. Applying these two laws to solve problems requires only consideration of the state of origin and the end, and does not involve the process of inquiring, which often brings many conveniences to solving problems. Some problems with inflectional work cannot be solved with Newton’s second law and uniform variable-speed movement knowledge.