In order to describe the velocity of two bodies after they collide, Newton developed a phenomenological equation known as "Newton\' s Experimental Law" (NEL). In this way, he was able to practically bypass the complication involving the details of the force that occurs during the collision of the two bodies. Today, we use NEL together with momentum conservation to predict each bodyś velocity after collision. This, indeed, avoids the complication of knowing the forces involved in the collision, making NEL very useful. Whereas in Newtonś days the quantity of kinetic energy was not known, today it is a basic quantity that is in use. In this paper we will use the loss (or gain) of kinetic energy in a collision to show how NEL can be derived.

中文翻译：

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恢复系数：从一般能量考虑推导出牛顿实验定律

为了描述两个物体碰撞后的速度，牛顿开发了一个现象学方程，称为“牛顿实验定律”（NEL）。通过这种方式，他实际上能够绕过涉及两个物体碰撞过程中发生的力的细节的复杂性。今天，我们使用 NEL 和动量守恒来预测碰撞后每个物体的速度。这确实避免了了解碰撞所涉及的力的复杂性，使 NEL 非常有用。在牛顿时代，动能的数量是未知的，而今天，它是一个正在使用的基本数量。在本文中，我们将使用碰撞中动能的损失（或获得）来说明如何推导出 NEL。