Talk:Gyroscopic exercise tool

Friction based explanation is wrong

This paper explains in detail how these things work; they start off by saying "Friction is neglected in this note for simplicity and to emphasize the main effects", which seems to me strong evidence that it does not work primarily by friction. — ciphergoth 16:44, 30 September 2008 (UTC)

I can't find that sentence anywhere in the paper. What it does say is: "In postulating constraints on the motion of the rotor, several conditions could exist at the contact point between the track and the rotor’s axle. These include frictionless sliding, sliding with friction, and rolling without sliding. We shall only consider the last case..." The paper goes on to discuss the static Coulomb friction required in some detail. Thanks for providing link--it is a good source, backing up the explanation given in the article.

If you don't believe it, and you have a powerball you don't mind temporarily destroying, sprinkle some graphite powder into it. It gets in the track, cutting down the friction, and you can no longer make the thing work (I've tried it!). With some time and effort, you can wash/wear the graphite off, and it will work again. Rracecarr (talk) 14:17, 1 October 2008 (UTC)

Actually, I don't think the friction explanation is correct. The reason friction was used in the O'Reilly paper is to aid in the analysis. They chose to analyze the system under the Coulombic friction regime. However, if you look at the other analysis in the Heyda paper, you'll see that friction is not necessary. I mean, think about it. If friction between the axle and the groove is what spins up the rotor, then the mating surface would have to move faster than the axle surface for velocity to increase - that would be way faster than your wrist could move. If you look at the relation between torque, angular inertia, and precession rate, it can be shown that applying the right amount of torque in the right direction (the direction of precession) increases angular inertia (and thus, angular velocity). I believe you when you say that reducing friction makes it hard to spin it up, but it's technically not impossible. Evilrho (talk) 00:11, 16 June 2010 (UTC)

I think here there is a misunderstanding of the difference between rolling with effectively single point contact (thereby producing static friction at the point of contact; the two surfaces do not move relative to one another) and slipping / sliding contact while rolling (in this case, as many other: dynamic friction coefficient << "static" friction coefficient). Let's perform a mind-experiment with a ball rolling versus sliding down a hill--in which case will the ball perform more revolutions? - Anonymous Jones, 20 July 2010 (EDT) —Preceding unsigned comment added by 68.55.181.230 (talk) 01:16, 21 July 2010 (UTC)

Could anyone find a new explanation for this system? The Princeton link does not work. — Preceding unsigned comment added by 2601:9:100:DC3:AC2B:5823:A0BA:8E40 (talk) 07:03, 4 June 2015 (UTC)

If it would have been about a friction it would have produced a lot of heat. And it would have taken much more faster movement of the wrist. Interesting would be to find the equation wich describes the process, but I find it too difficult to me. Thus, I'll try to illustrate the process. When the ball inside is spinning it's hard to turn the toy. When we do it, we put the energy to it. It should goes somewhere, so it is spinning up the ball. The faster the ball is spinning the greater energy is needed to turn it, but it's no need to do it fast (which would be if it was about friction). The vector of this turn should have a component which perpendicular to the axis of the ball and lies in the plane in which the axis of the ball moves in the toy (it is a ring). Linear analogue is rotating of mass on the rope (e.g. sling). First you make swing movements to spin it up, than you make very little movements but it takes a force to keep the rotation. Sorry, I can't give the equation. — Preceding unsigned comment added by Said5969 (talk • contribs) 20:44, 3 December 2016 (UTC)

Image replacement

I removed the overly-promotional image and moved the other one to the top section. I added a patent drawing to the "Mechanics" section. Unfortunately, that image is likely to be deleted from the Commons as a copyright violation. Sigh. davidwr/(talk)/(contribs) 02:52, 1 June 2014 (UTC)

Not having the blatantly promotional image is a good thing.

I question the appropriateness of the patent drawing that has been used. One immediate issue I have with it is that it is from 2008 and we do not have other dates in the article. These things have been around for 35+ years (one ref is from 1980). Having a patent drawing labeled as from 2008 gives the impression that these are new devices. Anyone that just comes to the page sees the drawing, that it is labeled as a patent and that the date is 2008. There is a natural assumption that the issuing of a patent implies that it is a new device. — Makyen (talk) 04:00, 1 June 2014 (UTC)

Good point. I'll remove the image if someone hasn't done so already. davidwr/(talk)/(contribs) 04:48, 1 June 2014 (UTC)

Archive_1 has long discussion on history of various brands of these things

A neutral summary of history and notable brands could be added ? - Rod57 (talk) 08:05, 17 May 2020 (UTC)

History

It would be a useful addition to have a section on the history of the development of this tool. Who invented it? How was it developed? BlueBellTree (talk) 04:32, 19 June 2024 (UTC)