Creating Animations and Interactions with Physical Models (Ralph Thomas)

Physics-based animations and interactions are becoming more common in UI. This page goes through some basic physical models and the kinds of interactions and animations that can be constructed from them. Scrolling on iOS is an excellent example of a physics-based interaction. When you drag your finger across the screen, the content tracks along with it, thereby scrolling, but when you lift your finger all of the physics magic happens: the content continues tracking with the same momentum and slows down under the influence of (virtual) friction. If you hit the end of the content, then the momentum goes into an overdamped spring which absorbs the momentum and returns you to the end of the content. (iamralpht)