坐在行驶的汽车里的乘客，司机说他静止，路旁的人说他前进得真快．可见，说物体是运动还是静止，要看是以另外的哪个物体作标准，这个被选作标准的物体我们把它叫做参照物．参照物可以任意选择，但在某些情况下，巧选参照物，可使研究的问题简化得多．请看以下两个例子．题目 Passengers sitting in a moving car, the driver said that he was still, people on the road said he was moving fast. It can be seen that whether an object is moving or stationary depends on which object is used as the standard. This object, which is selected as the standard, is called the reference object. The reference can be chosen arbitrarily, but in some cases, the reference can be selected to make the research problem much easier. Please see the following two examples. topic