Subject:
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Re: John Leo's opinion of "The West Wing"
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Newsgroups:
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lugnet.off-topic.debate
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Date:
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Thu, 3 Oct 2002 17:11:25 GMT
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Viewed:
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906 times
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In lugnet.off-topic.debate, Frank Filz writes:
> David Koudys wrote:
> >
> > In lugnet.off-topic.debate, Frank Filz writes:
> > > David Koudys wrote:
> > > > I often wondered what would happen if we were to drill an 8 foot hole
> > > > straight through the planet (of course, this idea assumes the core of the
> > > > earth to be a nice room temperature, not molten rock...) and if wer were to
> > > > jump down said hole--would we go past the center of the planet, slow down on
> > > > the way to the other surface and just basically bounce back and forth thru
> > > > the tunnel until we came to rest, free floating, at the exact center of the
> > > > planet?
> > >
> > > I've wondered this in the past also. If the planet were not rotating, I
> > > think the answer would be that your analysis is correct. Note that you
> > > would be in a zero-G environment (or close to it) at the center assuming
> > > the Earth is close to an evenly dense sphere (or at least each onion
> > > skin layer is of uniform density) since basic Physics says that at a
> > > point inside a sphere of uniform density, only that mass contained in
> > > the sphere centered at the whole sphere's center of gravity and having a
> > > radius equal to the distance the point is from the center of gravity is
> > > involved in determining the gravitational attraction, the "layer"
> > > outside that radius basically cancels itself out.
> > >
> > > With a rotating sphere like Earth, I think the problem is that you will
> > > crash into the side of the hole since you will retain the velocity of
> > > the surface, yet as you go down, the velocity of a point in the hole is
> > > lower.
Would it be a $#*crash*#$ into the side or more of a 'rubbing' every once in
a while to stop the sideways velocity.
Considering that gravity is pulling straight down, and the original velocity
from the surface spin is moving you east at whatever kph, would the gravity
effectively cancel out the sideways velocity over the distance of the
tunnel, even tho the closer you get to the center of the earth, the slower
the sideways velocity is along the tunnel.
I mean, there is this sideways velocity, but the farther the mass goes 'off
center' from straight down, the more gravity would tend to pull that mass
back to center.
It's like that old static experiment we did in science class, with the ball
of fuzz hanging from a thread, and taking that stick and rubbing it in our
hair and holding it close the the fuzz--if both the fuzz and stick are
identically charged, the fuzz would tend to be pushed away from the stick.
However, it can only swing out so far from hanging straight down because
gravity wants to pull it back to hanging straight down.
And reading Frank's example about the onion and the layers, the effective
mass for attracting an object is lessened as we fall down the hole--I think
this means that our 'terminal velocity' speed would lessen as we get closer
to the center, so does this, in turn, mean that the closer we get to the
center of the planet, the slower we would fall--that we wouldn't have to get
past the center before we start slowing down, due to being pulled back to
the center?
I wouldn't expect to fall thru the exact center of a tunnel--I have a
visual in my mind about a series of points along the tunnel with the two
forces acting on the points--gravity pointing straight to the center of the
sphere, and velocity incurred at the surface, pointing perpendicular to the
force of gravity (due east). In my little visual, the points closest to the
surface have more force (bigger arrows) in both directions, but as the mass
gets closer to the center, the arrows for both become smaller--gravity
becoming a smaller force due to the decrease in effective mass on an object
the closer it gets to the center, and easterly velocity being cancelled out
as we fall due to the effects of gravity pulling the mass back towards
center, thus achieving a nice gradual arc straight to the center. So maybe
the tunnel should be dug in a computed arc... ;)
Our momentum might be pretty close to nil once we reach the center and the
'bobbing back and forth until equilibrium is achieved in the exact center'
effect would be significantly decreased.
Anyway, just random thoughts.
<snip>
> Frank
Dave K
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Message has 1 Reply:
 | | Re: John Leo's opinion of "The West Wing"
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| Quoting David Koudys <dkoudys@redeemer.on.ca>: (...) I think it'll feel like you're rolling down a steep hill, constantly crashing against the eastern wall. (...) uh, why? gravity is pulling straight down, your momentum is at 90 degs to the force - (...) (22 years ago, 3-Oct-02, to lugnet.off-topic.debate)
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Message is in Reply To:
| | Re: John Leo's opinion of "The West Wing"
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| (...) Ok, that would eliminate the rotation. (...) Since your original problem statement assumed there was no problem with a molten core, I think it's also reasonable to assume the water isn't a problem (you can make a dam from all the earth you (...) (22 years ago, 3-Oct-02, to lugnet.off-topic.debate)
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