Rotational Center of Mass question

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SUMMARY

The discussion centers on the behavior of a rotating object in relation to its center of mass (CoM) under different gravitational conditions. When an object, such as a uniform stick, is spun at its CoM and released, it falls straight down while continuing to rotate around that point. Conversely, if spun off-center, it will not drop straight down but will instead fall sideways, influenced by its rotational motion. In a gravity-free environment, the object will still find its CoM upon release and will rotate around it, confirming that the CoM remains the focal point of rotation regardless of gravitational influence.

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  • Understanding of center of mass (CoM) concepts
  • Basic principles of rotational motion
  • Knowledge of gravitational effects on objects
  • Familiarity with physics terminology related to motion
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Physics students, educators, and anyone interested in understanding the dynamics of rotating bodies and the implications of center of mass in both gravitational and non-gravitational contexts.

Charlie Van Neste
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On earth, under the influence of gravity, when an object is spun/rotated and then released, it will find its center of mass and rotate around that as it falls. So, if you spun a very straight uniform stick at its exact center of mass say 1 meter off the ground and then released it, it will drop straight down: continuing to spin at its center of mass as it falls. However, if you spun it off center and released it, it will always find its center of mass but will not drop straight down, instead it will fall to the left or right (depending on which way you are spinning it). Hopefully that wasn't explained too confusingly...

Anyway here’s the question. In an environment without gravity, will a rotating object that’s spun off center naturally find its center of mass when released? Or will it just sit still and spin lopsided - if you catch my meaning. I seem to think it will always find its center of mass when rotating whether in the presence of gravity or not. Anyone know the answer to this? Thanks!

Note that when I'm saying spin, or spun, I'm referring to rotation. I'm also restricting the rotation to just 1 axis - although I think the same answer will apply to multiple axes of rotation.
 
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Your intuition is correct. The object will fly off in the direction its CoM was moving when it was released, and rotate around its CoM.
 
Excellent! Thank you very much for you help.
 

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