Can a Rotating Object in Space Curve its Trajectory?

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Discussion Overview

The discussion revolves around whether a rotating object in space can be designed to curve its trajectory, focusing on theoretical constructs rather than practical examples like curve balls in baseball. Participants explore concepts related to the center of mass, geometric center, and potential effects of rotation on trajectory in a vacuum.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes that a "dumbbell" object with uneven mass distribution, when thrown with rotation, could trace a sinusoidal path due to shifting center of mass during rotation.
  • Another participant asserts that the center of mass will move in a straight line or parabolic path if acted upon by gravity, challenging the initial assumption of curving trajectories.
  • A later reply clarifies that while the center of mass does not shift, the geometric center can exhibit sinusoidal motion when a heavy object is attached and spun, leading to a wobbling effect during linear motion.
  • One participant introduces the concept of Eulerian wobbles as a related phenomenon, suggesting further exploration of this topic.
  • Another participant mentions a minor effect in General Relativity where spinning gyroscopes experience different forces compared to non-spinning bodies, noting that this effect is unrelated to off-center motion.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of rotating objects in space, with some supporting the idea of sinusoidal motion while others maintain that the center of mass moves in a straight line. The discussion remains unresolved regarding the feasibility of sustained curving trajectories.

Contextual Notes

Participants acknowledge limitations in their understanding of terms like center of mass and geometric center, and there is a lack of consensus on the implications of rotation on trajectory in a vacuum.

pallidin
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Can an object be constructed in such a way that, when thrown WITH rotation in space, causes the object to curve in it's trajectory.
Now, I'm not referring to "curve balls" in baseball, because a curve ball in space will not curve.

Rather, I'm thinking somewhere along the lines of a "dumbell" that has less mass on one side versus the other, and is thrown in space with a rotational moment. Under that condition, I assume the center of mass shifts in a cyclic fashion during rotation, causing the trajectory to trace a sinusodal path. Is that correct?

If that is correct, is there some arrangement of a differential rotating mass that will perform a sustained curve in space as opposed to the above sinusodal motion?
 
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The center of mass will move in a straight line (or parabolic if acted upon by gravity)

n2extc.gif
 
dav2008 said:
The center of mass will move in a straight line (or parabolic if acted upon by gravity)

n2extc.gif

You are right, and I can see that my question was not worded correctly and that my use of term center of mass was also used incorrectly.
If you draw a circle around the wrench in your above .gif and place a "dot" at the center of that circle, one can see that the dot takes on a sinusodal motion as it travels the trajectory.
Granted, the center of mass does not "shift" as I erroneously suggested, but the geometrical center does indeed shift during rotation.

So, if I take a metal jar lid, glue a heavy ball bearing to the inside lip, spin it rapidy about the geometric center of the lid(NOT the center of mass) and then force this lid into a linear push across the table, the lid will wobble left and right as it traverses across the table, forming a sinusudal trace about the geometric center.

Perhaps the above description makes more sense as opposed to my incorrect initial question.
 
Look up on Eulerian wobbles.
 
arildno said:
Look up on Eulerian wobbles.

OK, thanks, I will. Appreciate the suggestion.
 
pallidin said:
Can an object be constructed in such a way that, when thrown WITH rotation in space, causes the object to curve in it's trajectory.
Now, I'm not referring to "curve balls" in baseball, because a curve ball in space will not curve.

This is probably not what you had in mind, but there is an extremely tiny effect in General relativity where spinning gyroscopes can experience a different force than a non-spining body of the same size and shape. Note that off-center motion has nothing at all to do with this tiny effect, it is caused by any sort of spin.

This effect is due to the coupling of the gravitomagnetic field to a spinning body, and is currently being tested (somewhat indirectly) by gravity probe B, and is described by the Papapetrou equations.

Wikipedia has only a stub on the topic :-(
http://en.wikipedia.org/wiki/Papapetrou-Dixon_equations
 
How interesting, thanks pervect.
 

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