Today’s report on yoyos ( http://www.straightdope.com/mailbag/myo-yo.html ) says that the ancient Greeks called it a “disk”. In my travels through old classical journals I found a reference to the yoyo as an “aristobolus”. I haven’t got the article here with me, but I copied it because I hadn’t heard that it was known in the classical world.
When I was an undergrad at MIT a group got together one January (between semesters, when they run a lot of short courses and odd projects) to build “The World’s Largest Yo Yo” It was about 3 feet in diameter, and looked like two outsized bicyckle wheels yoked together. They built a big metal “Finger” atop the Green Building (Building 54, the tallest on campus) and launched it off the top. It unrolled down to the bottom of its cable, then rolled about halfway back up. The finger couldn’t “pump” it back up, and it died.
Weeks later, the MIT student newspaper “The Tech” received a letter from the Army Helicopter Team. They had seen a news story about the “World’s Largest YoYo” at MIT (and its dismal performance), and said that they begged to differ. They had the World’s Largest YoYo. It was 8 feet in diameter, and they used an Army Helicopter (don’t know which type) as a platform to bounce it up and down – and theirs worked. A sad day for the 'Tute.
Sheesh – ZERO replies? All the comments on yoyos are going to other threads – and mine was FIRST!
I guess I even sink my OWN threads.
Don’t mind me. I’ll be over here in the corner…
Hey, don’t get me wrong, Cal, I think that the idea of an eight-foot yo-yo being bounced by helicopter is way cool… I just couldn’t think of anything to add that would top that.
::: imagining the yo-you string getting caught in the 'copter blades :::
Well, heck, just don’t want Cal to feel bad.
What would be the effect if you made yo yos that were not circular by either assymetric or some other shape, like an elliptical yo yo?
It should work just fine, as long as the axle is at the center of gravity. I think.
Wouldn’t it also depend on the distribution of mass? An ellipse is still fairly symmetrical. What about a yo-yo were made in the shape of a 3-4-5 right triangle (most asymmetric figure I can think of off the top of my head)?
I think that for any arbitrary shape, you could make it yo by putting the axle through the center of gravity, or even use different shapes (with the same mass and moment of inertia) for the two lobes. At least, I can’t think of any reason why that wouldn’t work. On the other hand, for a non-circular yo-yo, you’d have a chance of the string snagging on the corners. But then, this might pave the way for some interesting new tricks.
That’s kinda what I figured, but I thought it run it by somebody who knows this kind of stuff. Thanks!