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suppose there was an earth sized watermelon?



 
 
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  #1  
Old November 18th 04, 03:25 AM
neurocratic malfunction
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Default suppose there was an earth sized watermelon?

i know such a thing is not possible of ever existing, but suppose...

with a snap of a finger, planet earth turned into a giant watermelon.

what would happen?

this is my prediction. tell me if you think i'm right.

gravity would immediately collapse the watermelon and the center would
turn very hot due to the sheer pressure of the damn thing.

as the watermelon collapses, the liquid in the melon would burst out
of the cracked rinds and evaporate into gas. planet melon would keep
shrinking and shrinking until all the water boiled and evaporated and
only bits of burnt rinds would remain which would then drift off into
space like asteroids.

the question is would there be something like a planet of liquified
watermelon gas(mostly H20, i guess). i don't think so. i think for
there to be a gas planet, there has to be much more gas. that
probably means a jupiter sized watermelon, upon collapsing would have
enough gaseous matter to wield some kind of gravitational power over
the gas and hold it together. but earth is just too small.

can anyone create a computer model of this?
  #2  
Old November 18th 04, 03:28 AM
Mike Schilling
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"neurocratic malfunction" wrote in message
om...
i know such a thing is not possible of ever existing, but suppose...

with a snap of a finger, planet earth turned into a giant watermelon.
what would happen?


It would think to itself "Oh no, not again." If we knew exactly why the
watermelon thought that, we would know a lot more about the nature of the
universe than we do now.


  #3  
Old November 18th 04, 05:02 AM
Lewis Mammel
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neurocratic malfunction wrote:

i know such a thing is not possible of ever existing, but suppose...

with a snap of a finger, planet earth turned into a giant watermelon.

what would happen?

this is my prediction. tell me if you think i'm right.

gravity would immediately collapse the watermelon and the center would
turn very hot due to the sheer pressure of the damn thing.


So far so good.

as the watermelon collapses, the liquid in the melon would burst out
of the cracked rinds and evaporate into gas.


A naive misconception. This is like saying that the water at the bottom
of the ocean is under such pressure that it will come shooting
to the top in great geysers.

planet melon would keep
shrinking and shrinking until all the water boiled and evaporated and
only bits of burnt rinds would remain which would then drift off into
space like asteroids.


It would shrink into a hot ball of Hydrogen and Oxygen, at least.
I'm not sure if water would retain its molecular form at the center.
One thing is for sure, at those conditions there is no distinction
to be made between a gas and a liquid. Usually its called a gas.

Note that at the center of the sun, the density is far greater
than any metal - about 100 g/cc I believe. The atoms themselves
are squished out of existence so that the protons zing around
in a sea of electrons. The watermelon planet wouldn't go that far,
but I'm not sure what kind of conditions there would be.

Certainly, the whole thing could get hot enough so that it could
lose gas from the surface.

the question is would there be something like a planet of liquified
watermelon gas(mostly H20, i guess). i don't think so. i think for
there to be a gas planet, there has to be much more gas.


Not at all. You have it starting from a diffuse state,
( i.e. a watermelon ) so that it would gain a tremendous amount
of heat on collapsing, and probably would lose some mass. Starting
from a liquid water state, it would still compress and get hot,
but much less so.

that
probably means a jupiter sized watermelon, upon collapsing would have
enough gaseous matter to wield some kind of gravitational power over
the gas and hold it together. but earth is just too small.

can anyone create a computer model of this?


Some years ago, I made some notes on a gravitationally self-bound
gase - a gas planet. I think I was inspired by the cloud planet
in Star Wars. You do get tremendous compression at the center, so
you have to know the equation of state ( i.e. the behavior ) of
the gas under these extreme conditions.

I don't think you have to worry about the thing automatically
self-dissipating though. The compression won't "rebound". The
heat is associated with the pressure that slows the collapse.
As the heat dissipates, the collapse progresses. For planet
sized objects, you can easily end up with a low temperature
body ( after eons of cooling ) which nevertheless can sustain
the pressure at the center, and this goes for a water planet as well.

Oh yeah, I once calculated that if the earth were changed into
TNT, and detonated, the detonation would not release enough energy
to overcome the gravitational binding energy. The detonation
products would remain self-bound. Gravity rules at this scale.



.... I'm glad to see you've turned your mind to something productive.

Lew Mammel, Jr.
  #5  
Old November 18th 04, 01:47 PM
Gerry Quinn
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In article ,
says...
i know such a thing is not possible of ever existing, but suppose...

with a snap of a finger, planet earth turned into a giant watermelon.

what would happen?

this is my prediction. tell me if you think i'm right.

gravity would immediately collapse the watermelon and the center would
turn very hot due to the sheer pressure of the damn thing.


Not due to the 'pressure' as such, but due to the work done in
compressing the central parts. (Note that the Earth's rocks are already
compressed, though water would compress more. The Earth-size watermelon
would shrink to be smaller than the Earth is now, even a bit smaller
than the Earth would shrink if it were somehow uncompressed and left to
settle.)

as the watermelon collapses, the liquid in the melon would burst out
of the cracked rinds and evaporate into gas. planet melon would keep
shrinking and shrinking until all the water boiled and evaporated and
only bits of burnt rinds would remain which would then drift off into
space like asteroids.


Wrong. Let's assume for the sake of argument that we start with a ball
of water. How much it shrinks will depend on the equation of state of
water at high pressures. As it shrinks it will heat up, indeed - to
find out how much you would have to integrate pressure x area /
distance, and the distance in turn depends on the pressure of H2O at a
given density. Probably the latter would have to be estimated as some
pressures involved would be greater than testable in a laboratory.

My guess is that the core of the Earth would convert into a form of Ice
that is stable at relatively high temperatures and pressures (there are
about nine known forms of ice, all but one denser than water and stable
only at pressure). This would be quite hot. Outside it would be a
layer of water at boiling point (some miles deep - 50-100 perhaps?),
surrounded by a dense atmosphere of steam. If there was enough steam,
some would escape into space due to the Solar Wind or the gravitational
pull of other bodies. I would guess this would be a very small part of
the total water.

The temperature of the boiling sea would depend on the atmospheric
pressure. Whether heat from the centre would transmit as convection or
huge eruptions of steam, I can't say.

Pure energy conservation should tell you that the planet could not *all*
boil into space!

This would be an interesting physics problem and given a few hours I
could probably make ballpark estimates. However, I'm pretty sure of the
general trend as described above.

- Gerry Quinn


  #6  
Old November 18th 04, 06:38 PM
Karim Rashad
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On Thu, 18 Nov 2004 12:47:22 +0000, Gerry Quinn wrote:
(Note that the Earth's rocks are already compressed,
though water would compress more.


Isn't the basis of hydraulics that water isn't really compressible?
Though it might become solid after a certain amount of pressure,
presumably.

--
Karim Rashad remove SPAMFREE: krashad at SPAMorbisFREEuk dot com


  #7  
Old November 18th 04, 08:55 PM
John Zinni
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"Karim Rashad" wrote in message
news
On Thu, 18 Nov 2004 12:47:22 +0000, Gerry Quinn wrote:
(Note that the Earth's rocks are already compressed,
though water would compress more.


Isn't the basis of hydraulics that water isn't really compressible?


The basis of hydraulics is that water isn't VERY compressible and can be
thought of in gross terms as incompressible.

Google: Compressibility Water


Though it might become solid after a certain amount of pressure,
presumably.

--
Karim Rashad remove SPAMFREE: krashad at SPAMorbisFREEuk dot com



  #8  
Old November 18th 04, 09:21 PM
Wayne Throop
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:: (Note that the Earth's rocks are already compressed, though water
:: would compress more.

: Karim Rashad
: Isn't the basis of hydraulics that water isn't really compressible?

There's compressible, and then there's compressible.
Depends entirely on how much compressure is applied.
At the scale of the weight of a planet, water compresses
into Ice V or something. At the scale of several solar masses
in the space occupied by earth, EVERYthing compresses.

So, if water compresses when you set a planet on it, can Superman
(one of the older, stronger versions rather than the solar powered
wimps that have been in favor lately) squeeze a handfull of water to
produce Ice N ? If not, and if the reason why not is that the water
would squirt out between his fingers, then why *can* he make diamonds,
since at those pressures similar things apply to carbon.


Wayne Throop http://sheol.org/throopw
  #9  
Old November 19th 04, 03:31 AM
Karl Johanson
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"neurocratic malfunction" wrote in message

gravity would immediately collapse the watermelon and the center would
turn very hot due to the sheer pressure of the damn thing.


Wouldn't happen. Would be eaten long before by a Jupiter sized mutant
killer goat bee.

Karl Johanson


  #10  
Old November 19th 04, 08:48 AM
Nigel Waite
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Gerry Quinn wrote in message .. .

My guess is that the core of the Earth would convert into a form of Ice
that is stable at relatively high temperatures and pressures (there are
about nine known forms of ice, all but one denser than water and stable
only at pressure).


You mean that some-one really has discovered ice-nine ?

Cheers,
Nigel.
 




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