中学阶段应用动量定理解题的研究对象一般是单个物体,而应用动量守恒定律解题的研究对象一般是几个物体组成的系统,但如果把动量定理和动量守恒定律结合起来,研究一个物体系的运动规律,往往能带来许多方便,使问题大大简化. The research object of the application of the momentum equation in the middle school stage is generally a single object, and the research object of applying the conservation law of momentum is usually a system composed of several objects, but if we combine the momentum theorem and the law of conservation of momentum, we study a system of objects. The laws of movement can often bring many conveniences and greatly simplify the problem.