Weightless cats – Do space cats land on their feet? (2011) [video]

Re:Weightless cats – Do space cats land on their feet? (2011... by jameshart on Monday April 11, 2022 @04:46PM (#30994768)

But that’s a misunderstanding. Stable orbits are free fall.

There is no such thing as a stable orbit “at sufficient distance to not be influenced by” gravity.

There’s no such thing as a sufficient distance.

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Re:Weightless cats – Do space cats land on their feet? (2011... by e_y_ on Monday April 11, 2022 @05:41PM (#30995459)

I think more precisely, the traditional definition of an orbit (stable or not) is that it's influenced by gravity. You could be in a situation where the influence of gravity was negligible (say, far beyond any galaxy) but it wouldn't be considered an orbit at that point.

I guess certain multi-body situations like Lagrange points might make it debatable about which "direction" you're falling though.

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Re:Weightless cats – Do space cats land on their feet? (2011... by sacrosancty on Monday April 11, 2022 @08:24PM (#30997031)

I agree with mrexroad. Falling implies downward velocity. Free-fall is a different term that implies downward acceleration. For example, a ballistic projectile fired up that then falls back down first climbs, then falls, but it is in free-fall the whole time.

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Re:Weightless cats – Do space cats land on their feet? (2011... by pdonis on Monday April 11, 2022 @08:39PM (#30997151)

> Falling implies downward velocity. Free-fall is a different term that implies downward acceleration.

The GGP didn't say zero-g "is" falling. They said it's "the same as" falling. Which, for purposes of this discussion, it is, for the reason I gave--the key common property is being weightless, i.e., free falling.

Note, btw, that "free-fall" does not necessarily imply "downward acceleration". It just means "weightless". You could be weightless, in free fall, far out in deep space well away from all gravitating bodies, so that there is no well-defined notion of "downward acceleration" in your vicinity.

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Re:Weightless cats – Do space cats land on their feet? (2011... by sacrosancty on Sunday April 17, 2022 @01:12PM (#31062415)

Fair enough.

Regarding your second point, I think everywhere in the universe has some direction of the gravity field, however weak it is, and that would be the downward direction. But yea in some ideal place with exactly zero gravity, there's that special case.

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