Back when I was in graduate school, there was a Foucault pendulum hanging in an alcove outside the physics building. This was a rather large affair, stretching from the tenth floor to the third floor, which was at ground level. At the bottom was a heavy three-foot brushed-aluminum ball, and an electromagnetic device to keep it moving. This device did not work, and all the time I was there, the pendulum hung straight down.
I was studying for my final exam in Really Hard Differential Equations (better known as Classical Mechanics) one night, when a fellow student and I decided that a nice study break would be to try and get the Foucault pendulum moving again.
From the tenth floor.
With water balloons.
It turns out that a 3-foot metal ball is a lot harder to hit from 70 feet with a water balloon than it sounds. Before long, the alcove looked like the surface of the Moon, as the water balloons made craters in the gravel covering the ground. No problem, making the craters was fun, too — so much fun that when we ran out of balloons, we went out to buy more.
Eventually, though, we figured it would be best to get back to studying, so as a finale, we made the Queen Mother of all water balloons. I’m certain that it wasn’t actually a foot in diameter as I seem to remember, but it was big enough that we had to carry it up to the tenth floor in a bucket.
We dumped the bucket over the ledge, and watched it fall to the ground, at which point the safety glass separating the alcove from the building’s lobby went totally white. When we went downstairs to see what we’d done, there was a hole in the glass about ten feet above the ground.
Partly because we wanted to be honest, and partly because we figured we’d get caught anyway, we went to the campus cop shop and told them something along the lines of “there’s some broken glass at Stevenson Center. That was us, sorry. Send us a bill.”
We never got a bill, but I was talking to the department administrator a few months later, and he made sure to mention that they were pulling out the pendulum and putting in a picnic area because “you never know what sort of hijinks students are going to get up to next.” That was the last I ever heard of it, except from my sisters, who seem to remember the incident more distinctly than I do.
