同一直线上两个物体做相对运动时常常会涉及“追及”与“避碰”的问题,它们既有区别又有联系.正确解决这两类问题的关键在于掌握两个物体的位置坐标及相对速度存在的特殊关系. When two objects on the same line do relative motions, they often involve “recovery” and “collision avoidance.” They are both different and related. The key to correctly solving these two types of problems is to grasp the position coordinates and relative of two objects. The special relationship of speed exists.