Introductory mechanics courses use the bouncing ball model to familiarize students with the principles of binary inelastic collisions. Nonetheless, in undergraduate courses, the modeling of binary systems typically disregards the time of contact and the effects of gravity, which yields to a constant coefficient of restitution (COR) and, as a consequence, prevents students from elucidating the real dependence of COR with impact speed. In this work, we proposed a simple experimental setup to investigate the impact dynamics of a spring-mass body that bounces on a rigid plate as well as a theoretical framework that captures the velocity dependence of the COR for low-impact speeds. Our analytical expression for the COR highlights the role-played by gravity, impact speed and collision time on the collision dynamics. Our results suggest that the inclusion of gravity force allows an adequate estimation of the critical impact speed and maximum deformation distance, crucial parameters to differentiate between repulsive and attractive interaction regimes. Our experimental setup enables the clarification of several key concepts of mechanics while it is easy to be performed in most undergraduate laboratories.

力学入门课程使用弹跳球模型使学生熟悉二元非弹性碰撞的原理。但是，在本科课程中，二元系统的建模通常会忽略接触时间和重力影响，这会产生恒定的恢复系数（COR），因此，阻止了学生阐明COR的真正依赖性。冲击速度。在这项工作中，我们提出了一个简单的实验装置，以研究在刚性板上弹跳的弹簧质量体的冲击动力学，以及一个理论框架，该理论框架捕获了低冲击速度下COR的速度依赖性。我们对COR的分析表达式强调了重力，碰撞速度和碰撞时间在碰撞动力学中的作用。我们的研究结果表明，重力的引入使得可以对临界冲击速度和最大变形距离进行充分估计，这是区分排斥和吸引相互作用机制的关键参数。我们的实验装置可以阐明力学的几个关键概念，而在大多数本科实验室中却很容易执行。