Document Type

Conference Presentation

Publication Date

11-7-2015

Department

Physics and Astronomy

Keywords

laboratories, experiments, cameras, errors, measurement

Abstract

In video analysis lab experiments, students frequently find large discrepancies between results based on self-filmed videos and expected values (e.g. for g determined by a fit to projectile motion data). These differences are frequently far larger than the uncertainty calculated from their fit. Using an inexpensive point-and-shoot camera with a 4x optical zoom to record video, we investigated two possible causes of this error: the effect of placing the reference meter stick at a different object-to-camera distance and the effect of the motion of interest being in a plane not perpendicular to the camera lens. When we observed these phenomena for wide angle, normal, and telephoto focal length settings we found systematic errors as large as 40%. Based on our findings, we make recommendations for minimizing these errors.

Comments

Presented at the Iowa Section of the American Association of Physics Teachers Meeting held in Des Moines, Iowa, on November 7, 2015. Presented later by Dr. Zwart at the winter meeting of the American Association of Physics Teachers held in New Orleans on January 11, 2016.

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