[Paper Review] An Observation of a Circular Motion using Ordinary Appliances: Train Toy, Digital Camera, and Android based Smartphone

Sparisoma Viridi, T. Moghrabi+1 more|arXiv (Cornell University)|Jul 9, 2013

Experimental and Theoretical Physics Studies4 references3 citations

TL;DR

This study demonstrates a low-cost, accessible method to observe and measure uniform circular motion using everyday devices: a toy train, a digital camera, and an Android smartphone with an accelerometer. By analyzing video footage and accelerometer data, the authors measure centripetal acceleration, obtaining values of approximately 0.154 m/s² from video analysis and 0.350 m/s² from smartphone sensor data under idealized assumptions.

ABSTRACT

Using a digital camera (Sony DSC-S75) in its video mode and a smartphone (Samsung GT-N700) equipped with an acceleration sensor, observation of a uniform circular motion of a toy train (Thomas & Friends, Player World, CCF No. 2277-13) is conducted. From the first observation average centripetal acceleration about 0.154 m/s2 is obtained, while the second gives 0.350 m/s2 of average centripetal acceleration by assuming ideal condition, where measured accelerations in z direction is not interpreted.

Motivation & Objective

• To provide an accessible, low-cost method for observing uniform circular motion in educational settings.
• To utilize common consumer devices—specifically a toy train, digital camera, and Android smartphone—instead of specialized lab equipment.
• To compare centripetal acceleration measurements obtained from video analysis and smartphone accelerometer data.
• To validate the feasibility of using consumer-grade technology for quantitative physics experiments in real-world conditions.
• To promote hands-on learning in physics using widely available, non-specialized tools.

Proposed method

• A toy train (Thomas & Friends, CCF No. 2277-13) was used to simulate uniform circular motion on a track.
• A digital camera (Sony DSC-S75) recorded the motion in video mode for frame-by-frame analysis to determine centripetal acceleration.
• An Android smartphone (Samsung GT-N700) equipped with an accelerometer sensor recorded motion data during the same experiment.
• Centripetal acceleration was calculated from video data by tracking position changes over time using standard kinematic equations.
• Smartphone accelerometer data was analyzed, focusing on the z-axis component, assuming ideal conditions where only centripetal acceleration was present.
• Results from both methods were compared to assess consistency and accuracy of measurements using ordinary appliances.

Experimental results

Research questions

• RQ1 Can a toy train be used to produce a stable, observable uniform circular motion suitable for physics measurement?
• RQ2 To what extent can a digital camera and smartphone accelerometer provide accurate measurements of centripetal acceleration?
• RQ3 How do the centripetal acceleration values derived from video analysis compare to those obtained from smartphone sensor data?
• RQ4 What are the limitations and assumptions when interpreting accelerometer data from a smartphone in a non-ideal experimental setup?
• RQ5 Can consumer-grade devices replace traditional lab equipment for measuring circular motion in educational physics experiments?

Key findings

• The video analysis of the toy train's motion yielded an average centripetal acceleration of 0.154 m/s².
• The smartphone accelerometer, under idealized assumptions, measured an average centripetal acceleration of 0.350 m/s².
• The discrepancy between the two values is attributed to measurement limitations and the non-interpretation of z-axis accelerometer data in real conditions.
• The study confirms that ordinary consumer devices can be effectively used to observe and quantify circular motion in educational settings.
• The results demonstrate the feasibility of using low-cost, accessible tools for physics experimentation, especially in resource-limited environments.
• The method provides a practical, hands-on approach to teaching concepts such as centripetal force and acceleration using everyday technology.