Re: A newcomer here

In article <PrqVe.6937$b37.3139@trnddc04>,
"Logan Kearsley" <chrono.surfer@xxxxxxxxxxx> wrote:

> "David Friedman" <ddfr@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> news:ddfr-DAA931.18240812092005@xxxxxxxxxxxxxxxxxxxxxxxx
> > In article <GepVe.3508$XO6.2586@trnddc03>,
> > "Logan Kearsley" <chrono.surfer@xxxxxxxxxxx> wrote:
> >
> > > With constant crust thickness and density, the surface gravity
> > > increases as the radius increases.
> >
> > No. It stays constant.
> >
> > Area goes as the square of radius, so with constant thickness and
> > density mass goes as the square of radius.
>
> Except that it doesn't, exactly. It's somewhat off. Assuming constant
> density, the mass is dependent on the volume of the shell, which is the
> volume of the spherical world minus the volume of the empty spherical
> interior. This will only scale with the surface area / square of the radius
> if the ratio between the outer sphere and the inner sphere is constant, but
> if the shell thickness is constant, that ratio won't be.

Fair enough, but it's a small effect, and goes assymptotically to the
constant value you would get with an infinitesimally thick shell.

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