When iOS 7 came out, the animations were the first thing everyone noticed. Some people even claimed they got seasick watching their phones. Now we know why: those flat, pastel-colored cards can hit nearly 17 miles per hour as they zip toward your face.

Over at Buzzfeed, John Herrman and Jake Levy looked at some of the physics behind iOS 7 animations. When you open a homescreen app and it zooms in to fill your screen, it's moving toward you from an imaginary start point 5.33 feet away. Since the animation takes 0.8 seconds, that calculates out to 4.5 miles per hour. Jogging speed.

Opening apps from a folder really puts the pedal to the metal. Thanks to perspective, the tiny app icons inside a folder look like they're 19.29 feet away. Zooming in on a folder takes 0.8 seconds, meaning that folder flies toward your face at an average speed of 16.4 miles per hour. But since the icon speeds up in the middle of its trip and slows down toward the end, Buzzfeed estimates its top speed at over 20 miles per hour. That's like driving down a city street!


So maybe those people complaining of motion sickness weren't so crazy after all. The whole physics behind the animations is fascinating — check out the full article to learn more. [Buzzfeed]

Top animation by Gizmodo / Michael Hession; infographics by Buzzfeed / John Gara