Physics and Astronomy
laboratories, experiments, cameras, errors, measurement
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.
Zwart, John; Frisch, Kayt E.; and Martin, Tim, "Systematic Errors in Intro Lab Video Analysis" (2015). Faculty Work Comprehensive List. 418.