一些教学期刊和参考书经常讲解物理量及其变化率的问题,也经常有人提到“位移的变化率就是速度”。仔细推敲,这种说法不甚确切,值得商榷。首先我们要弄明白物理量变化率的含义。所谓某一物理量的变化率是指该物理量的变化量与发生这一变化所用时间的比值。例如,某量D的变化量记为ΔD Some teaching journals and reference books often explain physical quantities and their rates of change, and often it is mentioned that “the rate of change of displacement is speed.” Careful scrutiny, this argument is not exact, it is debatable. First, we have to understand the meaning of the rate of change of physical quantities. The so-called rate of change of a physical quantity refers to the ratio of the change of the physical quantity to the time taken for the change to take place. For example, the amount of change in a certain amount of D is denoted as ΔD