论文标题
额外的咖啡过滤器增加
The Added Mass of a Falling Coffee Filter
论文作者
论文摘要
掉落的咖啡过滤器是入门物理实验室课程中研究的常见对象。它们通常用于证明末端速度，并确定阻力如何依赖于该速度。但是，它们也可以用来证明空气影响下降咖啡过滤器的运动的其他方式。特别是，在静止的最初加速度期间，质量不同的流体力起作用，并导致这种加速度远小于真空中物体的加速度。使用声音运动传感器或视频分析，可以使用咖啡过滤器可以轻松观察到这种流体力，通常称为“添加质量”。在这里，为下降的咖啡过滤器测量了添加的质量。此外，计算了通过理想流体移动的咖啡过滤器添加质量的理论值。这两个值相对吻合。最后，显示了增加的质量与仅测量末端速度的实验相关。
Falling coffee filters are a common object of study in introductory physics laboratory classes. They are usually used to demonstrate the terminal velocity, and determine how the drag force depends on this velocity. However they can also be used to demonstrate other ways that the air affects the motion of the falling coffee filter. In particular, a qualitatively different fluid force acts during the initial acceleration from rest, and causes this acceleration to be much less than the acceleration of an object in vacuum. This fluid force, commonly known as the `added mass', is easily observable with coffee filters using either a sonic motion sensor or video analysis. Here the added mass is experimentally measured for a falling coffee filter. In addition, the theoretical value for the added mass of a coffee filter moving through an ideal fluid is calculated. The two values agree relatively well. Finally, it is shown how the added mass is relevant to experiments that only measure the terminal velocity.
