> On Thu, Dec 03, 1998 at 12:02:33AM -0000, Simon Kenyon wrote:
> > look, can we end this?
> > gravity is NOT, repeat NOT caused by spinning!
>
> Actually if the earth were to not be spinning we would all weigh a little more,
> however, the act of stopping the spin would be extremely destructive, and
> depending on how it was done could easily end most life on earth..
>
> For instance, if you stopped just the earth the lovely atmosphere would
> suddenly be moving quite quickly compared to the ground, as would the people,
> cars, etc...
Yes. Now we are moving at a rate of near 70 m/s for earth spinning.
The problem with sudden eart stop is that all the moving objects are
subjected to the inertia forces (this is one of the reasons that deny a
sudden stop of earth spinning, you have to furnish enought energy for
zeroing the motion quantity of the planet:
m * v + integral[0, r] {[dm(r) + dvr(r)]/dr}
where
v is the absolute velocity of earth seen as a point in the universe
vr is the rotational velocity
that is a very big quantity. You must know even that:
E = m * v^2 / 2 + I * w^2 /2
where
I is the inertia momentum
w is the rotational speed
and this energy, the energy owned by the earth in her actual state, is
high).
Of course even if you can do it, the atmosphere will not stop its motion
until the viscosity forces have slowed it down to zero and this should
need much time since air viscosity is not very high compared with, for
example, water. You can see this with a glass of water: with a stick try
to put the water in motion and then stopping stick motion you will see
that water will not stop istantaneously its motion but gradually decrease
its velocity until zero is reached after some time.
Ciao,
Riccardo.
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