The Leaking Drum
The Science Centre Singapore is collaborating with The Tech Museum on their web and Second Life platform The Tech Virtual, where anyone can design and prototype a science centre exhibit. Our topic is Water, and to try out the online tools I built a couple of prototypes for science-inspired fountains. This is the Processing version of one of them.
Water pressure increases with depth below the water surface. This is demonstrated here, where water shoots out much faster from the holes near the bottom of a water tank than from those near the top. For details of how this works and why the water jets all converge on a certain line, see the description on The Tech Virtual.
This applet shows four variations on the idea of a leaking drum exhibit. (Click inside the applet and press 1, 2, 3 or 4 to switch.) In the first version, imagine a ring of holes in a rotating disc that is fitted in the flat side of a rectangular tank. This would be hard to build as a real exhibit, but illustrates the principle nicely. The second version is probably the most instructive if you try to understand the physics involved. The third version is a reversal of straight and curved features, while the last version is an idea of how this might work as an exhibit.
This last version is similar to the Leaking Drum exhibit I built in Second Life.