Science > Physics > Tsunami, nuclear firepower, and shattering the moon
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Science > Physics |
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"" |
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30 Aug 2005 04:12:12 PM |
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Tsunami, nuclear firepower, and shattering the moon |
Questions for you all. Perhaps too vague, but I hope not.
The tsunami I refer to below is the one in Dec '04.
Thanks,
Hal
Here's a little thought experiment. Suppose we found a tiny
island in the ocean, and put every nuclear weapon in the world on
that island, and we rig them to go all at once. What kind of
tsunami would result, and how would it compare to the natural one
we just saw? (Radiation and fallout are secondary issues here.)
Here's another question: What size meteor would have to hit the
Indian Ocean in order to produce a tsunami equivalent to the one
we saw?
And finally: What kind of energy would it take to shatter the
moon into fragments (like the watermelons that the old comedian
Gallagher used to smash with a sledgehammer)? And how many nuclear
weapons would that translate into?
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| User: "Uncle Al" |
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| Title: Re: Tsunami, nuclear firepower, and shattering the moon |
31 Aug 2005 12:11:33 PM |
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wrote:
Questions for you all. Perhaps too vague, but I hope not.
Great opening, that.
The tsunami I refer to below is the one in Dec '04.
Here's a little thought experiment. Suppose we found a tiny
island in the ocean, and put every nuclear weapon in the world on
that island, and we rig them to go all at once. What kind of
tsunami would result, and how would it compare to the natural one
we just saw? (Radiation and fallout are secondary issues here.)
None. Tsunamis are gravity waves (NOT gravitational waves, doofus)
that go right to the oceen's bottom. Tsunamis are all but
undetectable until they arrive in shallows to chirp the energy. 50%
chance that the leadng edge is a node or antinode.
If you want a big slosh at continental rims, detonate a string of big
nukes at the bottom of an ocean deep trench and hope for massive
landslides into the hole.
Here's another question: What size meteor would have to hit the
Indian Ocean in order to produce a tsunami equivalent to the one
we saw?
Work the energy in both cases. Not all that big. Somewhere between a
railroad car and a fully loaded aircraft carrier coming in at 30
miles/second.
And finally: What kind of energy would it take to shatter the
moon into fragments (like the watermelons that the old comedian
Gallagher used to smash with a sledgehammer)? And how many nuclear
weapons would that translate into?
Look up its gravitational binding energy, or calculate it. Can you do
a quarter inch of algebra? One kilotonne equals 46.51 mg of energy.
E=mc^2. Calculate it.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
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| User: "Mark Martin" |
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| Title: Re: Tsunami, nuclear firepower, and shattering the moon |
30 Aug 2005 10:03:12 PM |
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wrote:
Questions for you all. Perhaps too vague, but I hope not.
The tsunami I refer to below is the one in Dec '04.
Thanks,
Hal
Here's a little thought experiment. Suppose we found a tiny
island in the ocean, and put every nuclear weapon in the world on
that island, and we rig them to go all at once. What kind of
tsunami would result, and how would it compare to the natural one
we just saw? (Radiation and fallout are secondary issues here.)
Here's another question: What size meteor would have to hit the
Indian Ocean in order to produce a tsunami equivalent to the one
we saw?
And finally: What kind of energy would it take to shatter the
moon into fragments (like the watermelons that the old comedian
Gallagher used to smash with a sledgehammer)? And how many nuclear
weapons would that translate into?
Last year's Indian Ocean quake had an estimated energy of 4.3 x
10^18 J, or 100 Gt of TNT. By comparison, the world stockpile of
nuclear weapons is only currently at about 8 Gt. So the scenario you
describe would generate a tsunami only 8/100ths as strong as the one in
2004. The energy in a wave is proportional to the square of its height,
so if we set off the nukes at the epicenter of the Indian Ocean quake,
the height of the wave washing over India would only be a little less
than 1/3 as tall as last year.
The size of a meteor doing the same amount of work depends on what
it's made of and how fast it's moving upon impact. If it's a big slug
of iron, traveling at 30,000 m/s, then it translates to a cube a little
over 100 m on a side. (Roughly the length of a football field. That's
about the size estimated for the impactor which excavated the crater in
Arizona.)
To shatter the Moon and propel the fragments away from each other
indefinitely requires work equal to its gravitational binding energy:
E = [(3/5)/GM^2]/r
E = energy
G = Newton's gravitational constant
M = the Moon's mass
r = the Moon's radius
In this case, E = 1.24 x 10^29 J, which is greater than the
megatonnage of the world's stockpile of nukes by a factor of a little
over 3 billion. Of course, if all you want is to break the Moon with
lots of cracks, but not explode it, then the job is some orders of
magnitude less impossible.
-Mark Martin
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