A phone emitting sound of a fixed frequency is sliding on an inclined plane and approaching a second phone kept at the bottom of the plane. The detected frequency versus time data by the second phone are used to calculate the acceleration of the sliding phone. The primary objective of this paper is to calculate the sliding friction between the phone and the plane from the acceleration values. It demonstrates that the sliding friction is constant irrespective of the inclination of the plane. Results are in good agreement with the one obtained from the video analysis.

中文翻译：

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使用多普勒效应和智能手机确定斜面的摩擦系数

发出固定频率声音的电话在倾斜的平面上滑动，并接近固定在该平面底部的第二个电话。第二电话检测到的频率与时间的数据用于计算滑动电话的加速度。本文的主要目的是根据加速度值计算手机与飞机之间的滑动摩擦。它证明了滑动摩擦是恒定的，与平面的倾斜无关。结果与从视频分析获得的结果非常一致。