Gyroscopic exercise tool: Difference between revisions

Revision as of 23:05, 19 August 2024

Revision as of 06:32, 24 August 2024

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[[File:Video of a complete use session with a gyroscopic exercise tool.webm|thumb|Video showing the use - from starting the rotation with a 'shoestring' over various movements with the holding hand until stopping the rotor with the second hand. The demonstrated speeds are, in part, very high and not recommended for normal exercise due to the high resulting forces.]]

A '''gyroscopic exercise tool''' is a specialized device used in [[physical therapy]] to improve wrist strength and promote the development of palm, wrist, forearm, and finger muscles. It can also be used as a unique demonstration of somecertain aspects of [[dynamics (physics)|rotational dynamics]]. The device consists of a [[tennis ball]]-sized plastic or metal shell surrounding a free-spinning mass, with an innera heavy inner core, which can be spun by a short rip string. Once the [[gyroscope]] inside is going fast enough, the person holding the device can accelerateincrease the spinning mass to higher rotation rates by moving thetheir wrist in a circular motion<ref>{{Cite journal |last=Heyda |first=P. G. |date=2002-09-12 |title=Roller ball dynamics revisited |url=https://pubs.aip.org/aapt/ajp/article-abstract/70/10/1049/310601/Roller-ball-dynamics-revisited?redirectedFrom=fulltext |journal=American Journal of Physics |volume=70 |issue=10 |pages=1049–1051 |doi=10.1119/1.1499508 |issn=0002-9505 |archive-url=https://web.archive.org/web/20170808024204id_/http://file.seekpart.com/keywordpdf/2010/12/3/201012316133421.pdf |archive-date=2017-08-08}}</ref>. The force enactedexerted on the user increases as the speed of the inner gyroscope increases.

==Mechanics==

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Angular acceleration occurs regardless of the direction of the applied torque, as long as it is sufficient. The device functions without fine-tuning the driving motion, and the tilting of the shell does not need to be in rhythm with the precession or at the same frequency. Since kinetic friction is almost as strong as static friction for the materials typically used, it is not necessary to apply exactly the amount of torque needed for the axle to roll without slipping along the side of the groove. These factors enable beginners to learn to speed up the rotation within a few minutes of practice.

Using the proportionality of the kinetic force of friction to the normal force, fk​=μk​Fn​, where μk​ is the kinetic coefficient of friction, it can be shown that the torque spinning up the mass is a factor of μk​(Rgroove​raxle​​) smaller than the torque applied to the shell. Since frictional force is essential for the device's operation, the groove must not be lubricated to ensure that the friction of the ring can enactexert a force on the gyro.

==References==