This animated tutorial, part of the Einstein Light website, presents the concept of relativity from a situation inspired by Galileo (an inertial reference frame). It shows the motion of a ball being dropped from two reference frames: on a moving train and on a stationary platform. How does the motion appear different to the observer on the platform and the observer on the train? The Einstein Light project is a qualitative introduction to relativity, developed for novice learners and built around the framework of Flash media files with narration, video, and animation. It explores concepts ranging from Galilean relativity through Einstein and quantum mechanics.

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