Explore the Hypothetical: What Happens to a Spinning Top with No Forces?

[JackFyre]

TL;DR Summary

A question on precession

I was just reading up about the Earth's three motions, and it was written that the 'wobbling motion' (precession) exhibited by the Earth, could be compared to that of a spinning top. Intuitively, I guessed that a spinning top wobbles because of the Earth's gravity, and I found out that the Earth's precession is a combined effect of the Sun's and Moon's gravitational pulls.
(Precession of the Earth's Axis - Home Cornell Astronomy)So my question is,
what would happen to a spinning top in a system where there are no forces acting upon it (apart from the initial force that set it rotating, of course)
Would it wobble, or would it just, stop?

 

[A.T.]

what would happen to a spinning top in a system where there are no forces acting upon it (apart from the initial force that set it rotating, of course)
Would it wobble, or would it just, stop?

Depends on what kind of wobble you mean. The torque induced precession would stop. But there is also a torque free precession (also called nutation).

Also note that not all axes of rotation are stable:
https://en.wikipedia.org/wiki/Tennis_racket_theorem

 

[Halc]

Intuitively, I guessed that a spinning top wobbles because of the Earth's gravity, and I found out that the Earth's precession is a combined effect of the Sun's and Moon's gravitational pulls.

A top precesses because there is a torque on it perpendicular to its axis of spin. The force of the surface upon which it rests is countered by gravitational pull on its center of mass which is not over the point of contact.

A planet precesses its axis of spin due to similar torque exerted by tidal forces from the sun and moon on the oblate shape of the planet which exert a torque attempting to align the spin with said external masses.

what would happen to a spinning top in a system where there are no forces acting upon it (apart from the initial force that set it rotating, of course)
Would it wobble, or would it just, stop?

It certainly wouldn't stop as that would violate conservation of angular momentum.
Most rigid shapes and stable non-rigid shapes (Earth) would just continue to spin without precession. But look at the link for the Tennis racket theorem in the prior post which illustrates the exceptions to this. In no instance is angular momentum not conserved in the absence of an external torque.

 

[DrClaude]