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Anyway, poor Croc.. boo for kuma!!
And Kuma did have to touch Luffy to repel the pain and fatigue.
So going by what we've seen in the manga, we can expect the sand to follow the same rules, and be easily pushed out into a big paw shape, like Kuma does with everything else, not limited by the rules you're describing.
But the fight's over, so I guess we're supposed to stop discussing it, haha. Interesting topic though!
For example: Kuma can push things. All sorts of things. He just simply pushes them into a big paw shape. It defies common sense because that's what DF powers can do. Like Luffy being made of rubber? How could his cells function if they were made of rubber? They wouldn't! No nutrients, not even water would pass through the cell membrane. Not to mention the fact that cells need to be made of very specific molecular compounds in the first place, so they couldn't be made of rubber. And Kuma couldn't possibly push something intangible like "fatigue" even if he's very skilled at pushing things. So putting arbitrary requirements on what/how Kuma can push things, based on our reality, is not applicable in One Piece, especially after we've been clearly shown that his power to push isn't limited to what/how things can be pushed, in real life.
The point is, Oda makes the rules for the One Piece world. So we have to go by those rules, and not over-analyze things when we've already been shown that something "just is," like Kuma's ability to push. (Also, Kuma would automatically be touching the sand, if it's inside his body.)
---------- Post added at 02:41 PM ---------- Previous post was at 02:28 PM ----------
BTW physics corner: particles of air don't really attract / repel, unless they're very close. The very-short-range repulsive force makes them pretty much the same as small hard rubber balls, which bounce off each other. The reason gas holds together is
a) it's in confined space
b) it's in a for example gravitational field
That means if there was no gravity, the atmosphere would immediately disperse.
SiO2, on the other hand, holds together by weaker intermolecular bonds. Grains of sand act like air particles (to a certain extent) in that they bounce off each other, but the effect is negligible due to much worse ratio surface/mass.
Not important, just force of habit
Last edited by 0Xellos; December 16, 2012 at 06:44 PM.
But in the mean time, Croc (or at least part of him) could be pushed into the ocean, or Kuma could push just the water in the air towards Croc (which would fly at a ridiculously fast speed, based on how fast he makes people fly to other parts of the world). Of course there are things Croc can do to put up a good fight, but based on Kuma's powers we've seen in the manga, I see more ways that are faster and more reliable for Kuma to win this battle.
---------- Post added at 04:49 PM ---------- Previous post was at 03:54 PM ----------
The (primarily) diatoms of air molecules have higher intermolecular forces than clumps of silicon dioxide making up the sand. This is due to several things, but is mainly a polarizability consideration, and is not inherently a surface-to-mass ratio consideration. (You were actually referring to frictional forces, which are also not proportional to surface area, but only to the magnitude of the force perpendicular to the surface.) Both are actually fluids. Not liquids, as that is different. But fluids. And the main differences between them are viscosity and mass density.
And also, no, gas doesn't hold together because of a confined space or being in a gravitational field. It actually holds together from both viscous forces and internal gravitational forces. Diffusion is what would cause the fluid to disperse. So if we look at the two fluids thermodynamically, at the same temperature (e.g. ambient temperature) we can expect a higher rate of diffusion for air than for sand. (This is where the particle mass consideration comes in, when we look at two fluids at the same average kinetic energy, i.e. temperature.) So in the presence of an external gravitational field (e.g. on Earth), the sand wouldn't diffuse much at all, and settle onto the ground into what we would call a beach or sand dune, and the air would diffuse more and settle on top of the sand layer, forming what we would call an atmosphere.
So there's a Chem 101 lecture, haha.
Anyway, the polls are closed, so it's past time to move on. I doubt Kuma will make it through next round, regardless.
and I'll let that be my last post on the subject, other than commenting on the in-depth science lectures, lol.
Last edited by Leonsagara; December 16, 2012 at 09:03 PM. Reason: needed to add something
Liquids (and gases) are fluids.
You're right about the polarizability causing intermolecular forces (London dispersion forces in case of air), but those are the very-short-range forces I was referring to. If you compare mean free path (order of tens of milimeters) to approximate distances from which non-negligible polarization arises (order of angstroms), you'll find out that polarization really only governs molecules when they're "colliding".
Viscous forces arise from forces between molecules, it's not good to put these together with elemental forces like London's or G. And internal gravitational forces are even more negligible than London forces. Take 2 molecules of N2 for example, at their mean distance, and calculate the ratio between energy of their field vs. mean kinetic. I get about 10^-30. Energy is not the best for comparison, but there's no doubt in this case. This is caused by both bodies having very low masses. In comparison, the same ratio for an N2 molecule close to the Earth's surface and Earth, vs. mean kinetic energy is 10^4.
So no internal gravity, and close range London dispersion (which btw drops much faster with distance than typical Coulomb force). Diffusion is right, but if there was no gravity, it'd be diffusion air-vacuum, which fits your explanation with sand, too.
I don't dare to definitely say much about how sand acts in comparison (what I said about that before were just "educated guesses" ), but I'm sure about typical air.
I've been in forums which you put science te explain Shonen Logic with powers, but nothing like that. Very exciting.
Btw, Crocodile cannot dry metal
Well, there are some more corrections to be made, haha. I suppose this'll be the last, as we aren't even talking about One Piece anymore! London forces are actually electromagnetic, so it's incorrect to arbitrarily separate forces into something you are calling an "elemental force," there's no such thing. We can talk about atomic forces (between atoms) vs. intermolecular forces (between groups of atoms). In the case of a gas or sand, we are looking at intermolecular forces.
And what you're attempting to do in your calculations is an electrostatics approach, which isn't valid for things like London forces. You need to be using an electrodynamic approach. Also, you're confused on your usage of kinetic energy. If both substances are at the same temperature, that means they have the same mean kinetic energy. Which in turn means if one substance is made of particles with higher mass, then those particles will be moving around more slowly, on average, than less massive particles.
Also, the internal gravitational forces are always present, but are negligible until you get to stellar scales. But the reason why I mentioned them is because viscous forces and internal gravitational forces are what actually hold a fluid together. An external gravitational field, like that of the earth, contains it, not holds it together. That's a very important distinction.
Anyway, the point that I was making was that Kuma couldn't possibly be touching each particle of air in order to push it all into a shockwave. He just puts his hands on "the air" and it pushes it into "a big paw shape." He put his hand on Luffy and pushed out Luffy's fatigue into "a big paw shape." Going by that simple rule, it's reasonable to assume he can put his hand on himself and push out the sand out (through whatever place it came in from, if need be) into "a big paw shape." My intention was to say that the rules in One Piece are a lot, lot simpler than we are making them... and then we got super complicated, hahaha.
Whatever, this is the place to do it, I guess!
Although we still haven't determined whether Kuma can push a solid object through a solid object yet.