I Rotational stability and Fosbury Flop questions

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The discussion centers on the physics of stability in high jumping and cycling, particularly the Fosbury flop technique and the dynamics of bicycle stability at higher speeds. It highlights that there is no single equation for bicycle stability; rather, it involves a collection of interrelated equations and parameters. Gyroscopic precession is noted as a key factor, where increased speed reduces the precession rate for a given torque. The conversation also touches on different types of stability, including slow, gradual changes versus rapid, potentially dangerous shifts like a "tank slapper." Overall, understanding these dynamics is crucial for both high jump techniques and bicycle safety at speed.
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Why are rotations more stable the faster they rotate and what is the consequence of the fosbury flop?
What is the consequence of the center of gravity passing below the rod in the high jump? Fosbury flop.
Which equation is responsible for a bike being more stable the faster it's driven? and in rotating things in general being more stable the faster they're rotating.
 
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Welcome, John!

Please, see:
https://www.pbs.org/newshour/science/the-not-so-hidden-physics-of-your-favorite-olympic-event

high-jump-physics-03-1200x675.png
 
John3022 said:
Which equation is responsible for a bike being more stable the faster it's driven? and in rotating things in general being more stable the faster they're rotating.
Bicycles are complicated. There is more than one thing going on. You should not expect to find a single equation with a single unknown called "stability". Instead, you will find a collection of inter-related equations with a plethora of parameters.

Gyroscopic precession in particular is a bit simpler. You are probably concerned with torque-induced precession: https://en.wikipedia.org/wiki/Precession#Classical_(Newtonian)

The faster something is spinning, the less precession rate you get for a fixed input torque.
The faster a bike is moving, the more centripetal force you get for a fixed yaw rate.
 
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Welcome to PF. :smile:

John3022 said:
Which equation is responsible for a bike being more stable the faster it's driven?
Which kind of stability? Stability when everything is mellow and changing slowly, or the loss of stability called a "tank slapper" at speed? (Full disclosure -- I saved my one and only life threatening tank slapper merging onto a freeway at high speed in an early morning commute, and installed a steering damper on my CBR600F4 the next week).

 
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