Learning the Resistance Coefficients of Pendulum Motion Using Balls of Various Sizes

초록

An optical system with a photogate was developed to measure the speed of a pendulum at the lowest point of motion to obtain the damping and the resistance coefficients of the pendulum. The photogate consisted of a photoresistor, a laser, a mechanical body, and a pendulum ball. A 3D printer was used to produce the mechanical body and pendulum balls of various sizes. Furthermore, an Arduino was used to automate the measurement of the speed at the lowest point of motion and increase the precision. It was found that the resistance coefficient was found to be proportional to the size of the balls, which is regardless of ball mass, consistent with the drag equation for a small Reynolds number. The developed instrument and program were applied to the experiment class, and positive results in education about air resistance was obtained. © 2021 The Korean Physical Society. All rights reserved.

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