Family, Fun, and Physics

This is my grandson John, throwing a rock into the water of Fern Ridge Lake near Eugene. We're talking a big rock, as you can see here:



Big rocks make big splashes, which fascinated John -- but not nearly as much as they fascinated me when I enlarged a portion of the 1/1500 sec shot.



So much is visible in that frozen instant of time (0.0007 sec.)!  The rock itself is continuing to push down into the water after expelling a window-thin sheet of water upward.  Through the "window glass," you can see a secondary shock wave getting sent backward.  But my favorite feature of the brief apparition is a set of concentric rings on the sheet itself, caused by water droplets striking it like pebbles dropped in a pond. (Click on the image to see this better.)

Grandson John did not need any photographic enlargements to be entertained however.  He kept it up all the way to sunset, splash after splash:



It was a glorious afternoon -- we enjoyed family, a gorgeous sunset, and Physics.