动量定理是动力学的重要规律.通常情况下,研究对象为一个质量一定的物体,它与其他物体只有一次相互作用.我们称之为“单体作用”.这样,对象明确、过程清楚,求解不难.对于连续相互作用的情形,研究对象怎样选取,相互作用过程怎样确定,都是必须考虑的.总的思路是做好转化工作. The momentum theorem is an important law of dynamics. Usually, the object of study is an object with a certain quality. It interacts with other objects only once. We call it the “single action.” Thus, the object is clear and the process is clear. It is not difficult. For the case of continuous interaction, how the research object is selected and how the interaction process is determined must all be considered. The general idea is to do a good job of transformation.