Re: [gundam] Gravity & Colony

Chien Ting Chin (
Fri, 5 Feb 1999 14:06:45 -0500 (EST)

On Fri, 5 Feb 1999, Mark Nguyen wrote:
> >How far from the interior wall of a O'Neal Island 3 cylander do you
> >need to be to be free of the "gravity"? I noticed that in both 0080
> colony, you could "float" 1 cm above the "ground" and expend no energy.
> The ground would be spinning by you, though; to people on the ground of
> the colony, you would appear to be skimming along the surface.

Err, Mark, I know you know the physics, but you are confusing the hell out
of Rodrick!

Let me try to explain in a simple way:

To be truly free of the gravity, you'd have to be on the axis of rotation.
(notice that the space docks are always on the axis of rotation (remeber
the game Elite?)). As you descend towards the "ground" (the interior wall
of the cylinder), the gravity you fell gradually increase propotional to
the distance from the axis of rotation. So assuming ground level gravity
is 1-G, then at half the distance from axis to ground, you will feel

Of course my explaination above is assuming you are rotating with the
colony (at least to avoid motion sickness :) So Mark is right, IF you are
not rotating with the colony then you will not "fall", but then you need
to move (relative to the people in the colony) at a speed of square root
of (9.8 / R) where R is the radius of the colony in meters. Pretty
reckless flying I would guess. As Mark said, you won't expend energy to
keep afloat, but you will still need thrust to deal with air resistance.
Since the internal atmosphere is rotating with the colony.

CHIN, Chien Ting
Dept of Medical Biophysics, Sunnybrook Health Science Centre
... o O *
Man is a bubble

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