Free! TRACKER is an open-source video modeling tool designed for physics education. It caught our attention in this Empirical Zeal article analyzing the validity of the now-infamous Kickalicious YouTube video. Using the laws of projectile motion and the center of mass principle, the author constructed a pen-and-paper model from known and assumed values (time, weight, gravity, velocity) and then compared the plotted function against a plot created from TRACKER. The results are uncanny -- apparently the Kickalicious guy is the real McCoy.
