“人船模型”是动量守恒定律应用的一个典型问题.一、动量守恒定律的四个性质1.矢量性:动量守恒定律是一个矢量方程.对于一维问题,应选取统一的正方向,凡是与选取正方向相同的动量为正,相反为负.若方向未知,可设为与正方向相同列动量守恒方程,通过解得结果的正负,判定未知量的? The “human ship model” is a typical problem in the application of the law of conservation of momentum. First, the four properties of the law of conservation of momentum. 1. Vectoriality: The law of conservation of momentum is a vector equation. For one-dimensional problems, one should choose a uniform positive direction. The same momentum as the positive direction is selected to be positive, and the opposite is negative. If the direction is unknown, the conservation equation can be set to the same column as the positive direction, and the unknown value can be determined by solving the positive and negative results.