I caught this video on Geekologie, and it made me laugh. This is a brilliant idea: a woman put a camera on a hula hoop, and then, well, hula'ed: [WARNING: some folks might feel ill watching this. I will not be blamed if you have to wipe vomit off your keyboard.]
[Note: at the end of the video there are links to other videos like it.] I found this fascinating. For one thing, the motion is slower than I would've expected. I suspect that may be due to an illusion when you watch from the outside as a hula hoop being used; humans are notoriously poor at judging rotating reference frames. After all, people still try to argue with me that centrifugal force isn't real, when it it quite clearly is
. Even more amazing to me was that I didn't get ill watching that video. I tend to get a seasick on a kid's swing or when reading in a car, so the fact I was fine watching this is weird. But I have pretty good 3D spatial reasoning, and have a lot of practice swapping reference frames -- trying to figure out when the Moon rises, what configuration planets are in, and how to point a telescope give you a lot of practice there -- so maybe that helped. Beats me. But I wonder what other weird change-of-frames would benefit from using this camera technique? That might make a fun series of videos.
Related posts: - When I say centrifugal, I mean centrifugal! - Space station gives physics a boost - You spin me right round baby right round - xkcd, wherein Randall Munroe and I agree