Redesigning an Experiment to Determine the Coefficient of Friction

(1) Pittsford Mendon High School, Pittsford, NY

Typical high school physics experiments that investigate friction coefficients usually use a weighted mass that is dragged across a surface and is attached to a spring scale; the spring scale measures the frictional force occurring in the system. In such an experiment, a constant velocity (zero net force) is necessary in order to ensure that the measured force is only the friction force. While this configuration is simple to conduct and construct, it can be rather difficult to maintain a constant velocity of the weighted mass and to read the moving spring scale at the same time, which may result in large errors. We attempted to solve these issues by designing a new friction-coefficient experiment involving only static measurements. To conduct our experiment, we slid a block down a sloped surface and observed where the block landed. By measuring the horizontal distance of the block’s landing location, we could definitively derive the kinetic friction coefficient between the wood block and the sloped board. The standard deviation from our newly designed experiment is ~3 times smaller than that of the traditional experiment, which demonstrates that our experiment may be a viable replacement for standard high school physics experiments on kinetic friction. This experiment can also enhance the learning of physics topics like Newton’s second law, motion in two dimensions, friction, and programming.

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experimental design kinetic friction physics