[Archive!] Pure mathematics, physics, chemistry, etc.: brain-training problems not related to trade in any way - page 525

[Sceptic Philozoff]

Hardly relativism here, Andrew. In any case, physicists try to explain with the help of this hypothesis sudden changes of geographicalbelts of the Earth, which were in its history.

Here, perhaps, it is a matter of instability of rotation of a body around the "mean axis of inertia". I am not a mechanic, but I think this is where to dig.

[---]

Mathemat:

It's probably about the instability of the body's rotation around the 'mean axis of inertia'. I'm not a mechanic, but I think this is where to dig.

And it's most likely in the levers.

[Dmitry Fedoseev]

You need less torque to rotate along the long axis than the other axes. It is not possible to apply force exactly in the centre when throwing. If you try hard enough with the book, you can spin without flipping. When rotating along the shortest axis, there is also a gyroscope effect.

[Dmitry Fedoseev]

sergeev:
and most likely in the levers.

In these videos, the centre of mass does not correspond to the centre of rotation.

[TheXpert]

Integer:
In these videos, the centre of mass does not correspond to the centre of rotation.

How is that?

[михаил потапыч]

TheXpert:
How's that?

a rotating object looking for the optimum distribution

[михаил потапыч]

And in reality, in weightlessness, the letters don't cling well to the pages and gradually slide off to the edge, changing the centre of mass )

[TheXpert]

Mischek:
a rotating object is looking for the optimum distribution

Then it is not the Janibekov effect :) . The centre is on the axis of rotation and does not make oscillatory movements. Or rather at the point of rotation for the unstable case.

[TheXpert]

Who has a 60+ fps camera? It should be easy to do with a box of matches.

[михаил потапыч]

TheXpert:
Then it is not the Janibekov effect :) . The centre is on the axis of rotation and does not make oscillatory movements. Or rather at the point of rotation for the unstable case.

we see only a small part of the process, if you spin the book in a vacuum to make it rotate longer, sooner or later it will reach the optimum distribution.

and here it's just the very beginning and is stated as a whole with unexpected properties