We use videos taken with a mobile phone to study conservation of energy, conservation of momentum, and the work-energy theorem by analyzing the collision of a cue ball and the eight ball. A video of the full time sequence, starting from before the cue ball is struck until well after the collision, is recorded with a mobile phone. The video is imported into Origin (free to teachers and students taking a class) [OriginLab Corporation, Origin, Version 2020 (OriginLab Corporation, Northampton, MA, USA, 2020)], where the coordinates of the balls are digitized frame-by-frame using the free Video Extractor app. From these data, the velocities are determined as a function of time and used to determine the energy and momentum of each ball. The data suggest that the balls slip through part of their motion when rotating at an angular velocity different than the rolling angular velocity, so angular momentum and frictional torque must be considered. Such experiments require no specialized equipment other than a device to take a video, and the act of digitizing the data provides the student with visual reinforcement of the physics. Experimentation by students outside of campus can be fun for them and provides a useful alternative to classes when in-lab experiments are not practical. Use of a mobile phone in this way is generally applicable to any other mechanical phenomena that involve motion.

中文翻译：

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用手机收集数据：能量和动量守恒等力学定律的研究

我们使用手机拍摄的视频，通过分析母球和八球的碰撞来研究能量守恒、动量守恒和功能定理。用手机录制了从击球前到碰撞后的完整时间序列视频。视频导入Origin（上课老师和学生免费）[OriginLab Corporation, Origin, Version 2020 (OriginLab Corporation, Northampton, MA, USA, 2020)]，其中球的坐标逐帧数字化-框架使用免费的 Video Extractor 应用程序。根据这些数据，速度被确定为时间的函数，并用于确定每个球的能量和动量。数据表明，当以不同于滚动角速度的角速度旋转时，球会滑过其运动的一部分，因此必须考虑角动量和摩擦力矩。这种实验不需要专门的设备，只需要一个设备来拍摄视频，并且将数据数字化的行为为学生提供了物理的视觉强化。学生在校外进行的实验对他们来说很有趣，并且在实验室内实验不切实际时提供了一种有用的课堂替代方法。以这种方式使用手机通常适用于任何其他涉及运动的机械现象。将数据数字化的行为为学生提供了物理的视觉强化。学生在校外进行的实验对他们来说很有趣，并且在实验室内实验不切实际时提供了一种有用的课堂替代方法。以这种方式使用手机通常适用于任何其他涉及运动的机械现象。将数据数字化的行为为学生提供了物理的视觉强化。学生在校外进行的实验对他们来说很有趣，并且在实验室内实验不切实际时提供了一种有用的课堂替代方法。以这种方式使用手机通常适用于任何其他涉及运动的机械现象。