npsm 새물리 New Physics : Sae Mulli

pISSN 0374-4914 eISSN 2289-0041


Research Paper

New Physics: Sae Mulli 2013; 63: 411-415

Published online April 30, 2013

Copyright © New Physics: Sae Mulli.

Improved Linear Air-track Experiment with a Photo-interrupter Array

Taejoon KOUH, Zeehoon JANG*

Department of Physics, Kookmin University, Seoul 136-702, Korea



The linear air-track experiment system has been modified with an array of 256 photo-interrupters attached on the sides of the air track to follow the positions of the gliders in motion. The triggered signal from the array is used to locate the positions of the gliders on the track, and timing information is acquired from the system clock of the computer. Based on the measured values of the positions and the time, we were able to analyze the motion of the gliders on the track. Furthermore, with this modified experimental setup, we performed an elastic collision experiment on two gliders and verified conservations of momentum and energy. When compared to those from the conventional two-photo-gates setup, our experimental results show that the photo-interrupter array technique can provide much more accurate real-time determinations of the positions and the time of gliders in motion. The improved linear air-track system utilizing the photo-interrupter array will be highly beneficial in introductory physics laboratory courses.

Keywords: Linear air track, Momentum conservation, Energy conservation, Photo-interrupter

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