Friday, June 06, 2014

Physics of Yo

I've seen some good yoyo-ers and I've seen some young yoyo-ers, but 6-year-old Kazuya Murata really stands out in both categories.




The yoyo has sure come a long way since I was a kid. I remember learning a lot about physics from my old Duncan Butterfly - including the difference between static and dynamic friction.


See, back in the day, yoyos didn't come with bearings and clutches. Instead, you had a plain old string and some wax. You could either wax the string where it went around the yoyo axle, or if you were a little more serious, you could disassemble your yoyo to wax the axle directly.

I recall that the wax was a bit tacky if you put it on a cold surface and touched it, but it would get very slippery when you rubbed it or it got a bit warm. This is an excellent combination of properties for the yoyo. It would grip the string when the yoyo was rolling down or coming back up because the string wasn't sliding around the axle at those times. When the yoyo reached the bottom of its travels and started to sleep, the wax provided a very low friction contact between the string and axle. And low friction is the key to sleeping.

I don't know what type of yoyo the amazing Kazuya Murata is using in this video, but I'm sure it ain't wax that lets it sleep so long. Wax is good, but it's not that good. There's probably a very high quality bearing at the center. Still, this kid has some serious skills.

To learn more about the physics of the yoyo, check out the HowStuffWorks page on yoyos. Or just watch the video again to enjoy the the art of physics in action.

For those of you interested in vintage yo, here's Tommy Smothers doing some impressive stuff with some old-school waxed-string yoyos in the days before yoyo bearings and clutches.





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