.....if you take a look ( and a hoop...) at /from: https://en.m.wikipedia.org/wiki/Hoop_rolling (https://en.m.wikipedia.org/wiki/Hoop_rolling)
...and add/play a diameter/tube containing a (spring-free sliding mass-spring) system , as :
https://scienceworld.wolfram.com/physics/SpringsTwoSpringsandaMass.html (https://scienceworld.wolfram.com/physics/SpringsTwoSpringsandaMass.html)
Al_ex
Similar to the imbalanced flywheel,
There is a situation where we observe beneficial gravitational gains,
and a situation where we observe detrimental gravitational deficit.
Coincidentally, these are 180-degrees apart, and motion becomes a sole
result of E-in.
However, after considerable thought..:
If said spring system were suspended in a floating mechanism within a fluid....
(like the eyeball ball that always looks up)
Hmmm
Hi !
Let's SEE the possible evoluțion of a bicycle rim hoops toy :
https://en.m.wikipedia.org/wiki/Hoop_rolling#/media/File%3ABoys_with_hoops_on_Chesnut_Street.jpg
...to a possible adult "toy", if we add/test a diameter containing a linear oscillating mass/"atom" (spring-free sliding mass-spring) system,as:
https://www.britannica.com/science/spring-force
....a mass held by springs (the center of mass ) playing gravity and rotational inertia.
Al_ex