B A flip of the Earth on its axis

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The Earth does not flip on its axis, as its rotational axis is stable due to factors like its equatorial bulge and gravitational interactions. A model using a spinning ball can demonstrate flipping, but it does not accurately represent Earth's dynamics, which involve complex forces and energy conservation. Discussions highlighted that while models can show instability and flipping, they fail to account for Earth's non-rigid nature and the conservation of angular momentum. The conversation also touched on the challenges of replicating flipping effects in experiments with lighter objects, like table tennis balls, due to air friction and energy dissipation. Overall, the consensus is that Earth's axis remains stable and does not undergo flipping as suggested by some experimental models.
  • #31
Thanks for the info!
 
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  • #32
arydberg said:
Also on the subject of table tennis balls if you weight one half of the ball. by spliting it in two, filling one half with epoxy and glueing it back together and color the weighted half it sits with the weighted half down but when spun it will flip. It is stable when spinning only with the weighted half on top. You can also drill a hole in the ball, half fill it with water. and freeze it and color the weighted half. It workes fine for a short time till the water melts.
What is the spin axis with respect to the halves?

The half filled balls give you no clear intermediate axis. And your center of mass is not the ball center, so you have substantial external torques around the CoM from the air cushion support. This is likely quite different from the typical intermediate axis flipping.
 
  • #33
In order to get the most intriguing demo, is it better to have the three principal MoIs fairly close to each other, or is it better if they are as different as possible?
 

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