The Atwood machine experiment assisted by smartphone acceleration sensor for enhancing classical mechanics experiments

Abstract

Newton's second law can be demonstrated by classical mechanical experiments, one of which is using the Atwood machine. Atwood machines consist of two weights suspended by a rope and connected by a pulley. In this study, an Atwood machine experiment was carried out, where the smartphone was placed on one of the loads, so that the vertical acceleration of the motion system could be measured easily using an acceleration sensor. We also consider the effect of pulley rotation which is usually missed from previous studies. By deriving the second law equation of Newton on rotational and translational motion, we can get the relationship between the system acceleration and the gravitational acceleration of the earth. The results of the earth's gravitational acceleration obtained, compared with the results of the experiment using a stopwatch (conventional method), and with the value of the standard earth gravitational acceleration at that place. Earth's gravitational acceleration from the experiment using a smartphone is closer to the standard earth gravitational acceleration value than using a stopwatch. So, in this experiment, the use of a smartphone acceleration sensor contributes to enhance a conventional demonstration of classical mechanics experiments.