StephenOrnes at sciencenews.org reports that scientists have measured the speed of air escaping the column that is formed when a rock thrown into a flat body of water, like a pond.   When the column collapses, the air that is pushed out moves faster than the speed of sound (760 miles an hour.)  To read more and watch a video, go to http://www.sciencenews.org/view/generic/id/55900/title/FOR_KIDS_Supersonic_splash_.