一、运动与静止通常说的运动和静止都是相对于某一参照物来说的，是相对的，它们在一定的条件下可以互相转化．例如，可以把动的问题转化为静的问题而使求解简化．例1在同一轨道上做直线运动的甲、乙两车，甲以速度v1做匀速运动，乙在甲后以速度7）v2（v2＞v1）运动．乙在距甲s First, movement and stillness Generally speaking, motion and stillness are relative to a reference object and they are relative. They can be transformed into each other under certain conditions. For example, the problem of motion can be transformed into a static problem that simplifies the solution. Example 1 A and B vehicles that perform linear motion on the same track, A is moving at a uniform speed with speed v1, and B is moving at a speed of 7)v2 (v2>v1). B at distance from A