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Does Zoro produce enough aerodynamic lift here according to the Bernouilli's principle?

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Posted (edited)

This clip right before he cuts the stone golem, would you say he is experiencing more drag or does he in fact experience less drag where he applies his cut because of the Bernouilli's Principle?

"A wing provides aerodynamic lift through the camber (curvature) of its surfaces. Because the upper surface is more highly cambered than the lower surface, the air moving over the top surface is forced to move more quickly. This results in a lower pressure on the upper surface as compared with the lower surface and results in aerodynamic lift (Bernoulli's Principle)".

The claim among some of his fans is that he acted against drag and as such had no help when he was launched (see how he is thrown). I don't exactly how how legit this argument from mine is, but I said that there is going to be a boundary layer where the air pressure is much lower, as there is a streamflow that is created from Zoro's fast flight which would in theory result in lower pressures above him, and because he was thrown he had extra momentum on top of lower air pressure where he cuts it. In the clip you see at 1:52 sonic booms following in his track, and in the manga (which is the primary canon) you see the sonic booms really clearly 008.jpg so how fast would you say in Mach is he travelling here?

 

How would you judge this feat from a physics standpoint? Did his being thrown and the Bernouillis principle aid in cutting the stone golem, or was it a hindrance due to drag build up?

Grateful for any input!

Edited by Kyros

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Why are you posting this in a science forum?

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3 hours ago, Kyros said:

How would you judge this feat from a physics standpoint?

Personal opinion: The display of magical creature (stone golem) and breaking of Newtons laws in the movie clip makes me think that laws of physics, as we know them, are not part of the canon of this manga. An analysis from a scientific or physics point of view is not of any use.  

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!

Moderator Note

This does not seem appropriate for the physics section. Moved to the Lounge

 

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Posted (edited)
48 minutes ago, dimreepr said:

Why are you posting this in a science forum?

Because it's a question that is science related

 

30 minutes ago, Ghideon said:

Personal opinion: The display of magical creature (stone golem) and breaking of Newtons laws in the movie clip makes me think that laws of physics, as we know them, are not part of the canon of this manga. An analysis from a scientific or physics point of view is not of any use.  

The clip is the anime, I can post the manga itself (should've done that instead)

Here in the actual manga he does not make backflips in the air nor does he spin around his blades like that (I suppose that's the laws of Newtons you referred to as being broken). Disregarding the fact that the guy can turn into a golem (and Zoro possessing superhuman durability to withstand the heating effects of the air), how would you view the cutting feat from the perspective of drag and Bernouilli's principle? Would there be a reduction in the air pressure because of the speed of the streamflow that is created when he is flung at that immense speed (and would the imparted momentum help in the cutting, or, as others posit, just result in drag force that he would need to act against in order to cut the golem)? 

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1 hour ago, Ghideon said:

Personal opinion: The display of magical creature (stone golem) and breaking of Newtons laws in the movie clip makes me think that laws of physics, as we know them, are not part of the canon of this manga. An analysis from a scientific or physics point of view is not of any use.  

Would you say the cutting here can be defined as a shear force or how would you characterise the force applied?

Can I say the force applied = area of the cut times the shear strength of stone?

Is this a shearing force (there is no counter force in the opposite direction so I'm not sure what to call this force)

Edited by Kyros

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Posted (edited)
6 hours ago, Kyros said:

Disregarding the fact that the guy can turn into a golem (and Zoro possessing superhuman durability to withstand the heating effects of the air), how would you view the cutting feat from the perspective of drag and Bernouilli's principle? Would there be a reduction in the air pressure because of the speed of the streamflow when he is flung at that speed? 

Since this is the lounge I'll do some less rigorous analysis showing why science is of no use.

Observations in the movie clip. 
1: Zoro does not seem to follow the trajectory of a massive object; heigh above ground seems maintained.
2: Zoro does not seem affected by air resistance; speed is not reduced during the flight
3: There is atmosphere on the world where the fight takes place.

1: means that (a) Zoro is either massless* and hence unaffected by gravity or (b) neutrally buoyant in the atmosphere, like as a hot air balloon.
2&3: means Zoro could be (c) extremely dense, having extreme momentum. 

But (c) can't be compatible with 1, massive object fall down. And (b) is not compatible with 2, balloons stop quickly when thrown in air.
(a) is pointless, a massless Zoro, swords included, would have zero effect on a stone golem; there is no kinetic energy or momentum that can affect the golem.

That means Zoro travels through air by magic because the described airstrip is physically impossible. I do not know how magic affects drag and Bernouilli's principle, so again:

6 hours ago, Ghideon said:

An analysis from a scientific or physics point of view is not of any use.  

 

Side note: That fact the manga story is failing to describe physically probable action does not mean I can't see it as entertaining. I enjoy entertaining stories, if the canon of the universe where the events take place allow magic, faster than light travel etc I don't care how impossible that might be according to mainstream science. I just chose to not mix my interest in science and engineering into the events of fiction and fantasy in the story.  

 

*) I know that would mean a photon speed of c in vacuum and massless bodies of macroscopic size does not exist AFAIK; creating one would require magic. But this is the lounge after all, and we will get to the point anyway.

Edited by Ghideon
clarifications

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Posted (edited)

Nice discussion, Ghideon. +1

The only author of fiction that I know of who thought everything through from a physical point of view is Arthur C. Clarke. His novels had the distinct flavour of real science the way it could be or have been. This results in a much less action-driven narrative, more reflective. Overall very different.

There's a reason why science fiction is called science fiction and not fiction science. Some mangas are really very imaginative and entertaining, as Ghideon says. But that's all. There's no physics in most of them, I'm sorry to say. The phenomenon why you accept that for the sake of entertainment is called suspension of disbelief.

Quote

Suspension of disbelief, sometimes called willing suspension of disbelief, is an intentional avoidance of critical thinking or logic in examining something surreal, such as a work of speculative fiction, in order to believe it for the sake of enjoyment.[1] Aristotle first explored the idea of such a concept as it relates to the principles of theater; the audience ignores the unreality of fiction in order to experience catharsis.[2]

https://en.wikipedia.org/wiki/Suspension_of_disbelief

Edited by joigus

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Posted (edited)
11 hours ago, Ghideon said:

Since this is the lounge I'll do some less rigorous analysis showing why science is of no use.

Observations in the movie clip. 
1: Zoro does not seem to follow the trajectory of a massive object; heigh above ground seems maintained.
2: Zoro does not seem affected by air resistance; speed is not reduced during the flight
3: There is atmosphere on the world where the fight takes place.

1: means that (a) Zoro is either massless* and hence unaffected by gravity or (b) neutrally buoyant in the atmosphere, like as a hot air balloon.
2&3: means Zoro could be (c) extremely dense, having extreme momentum. 

But (c) can't be compatible with 1, massive object fall down. And (b) is not compatible with 2, balloons stop quickly when thrown in air.
(a) is pointless, a massless Zoro, swords included, would have zero effect on a stone golem; there is no kinetic energy or momentum that can affect the golem.

That means Zoro travels through air by magic because the described airstrip is physically impossible. I do not know how magic affects drag and Bernouilli's principle, so again:

 

Side note: That fact the manga story is failing to describe physically probable action does not mean I can't see it as entertaining. I enjoy entertaining stories, if the canon of the universe where the events take place allow magic, faster than light travel etc I don't care how impossible that might be according to mainstream science. I just chose to not mix my interest in science and engineering into the events of fiction and fantasy in the story.  

 

*) I know that would mean a photon speed of c in vacuum and massless bodies of macroscopic size does not exist AFAIK; creating one would require magic. But this is the lounge after all, and we will get to the point anyway.

Thanks for the detailed answer! But you're approaching this as if this is a world of magic where the author throws scientific laws to the wind and is all willy nilly with science - and that's not at all what this series is about! At the clip I will show below for reference, the guy being hit is made out of smoke (you need to imbue your weapon with a special coating in order to be able to hit him which is what the balck stuff is) but just because there are these elements in the story doesn't mean that he bends the overall laws of science.This is a series where powerscaling (the activity of assigning power levels to characters based on their showings) is a BIG THING! This wouldn't be possible or consisent if the author was inconsistent and messy with the science. I am working under the assumption that the author has insight into and is trying to follow physics as best he can, as he is trying to create a consistent and coherent world, and here the laws of physics aren't different from ours: it's just that the parameters are diferent. Such as

(1) people in this verse are stronger and more durable,  and as such Zoro (at the hgher echelon of superhumans trength) here is durable enough to withstand the heating effects of the air (that would result from what can be seen from the trail of sonic booms as supersonic flight.

and

(2) the guy throwing him is physically strong enough to launch him at such a speed that he has (despite not being perfectly streamlined like an airfoil) he is actually flying at such a high speed that the lift is generated is enough to counter gravity; and of course Zoro's speed is slowed down, it's just that his launch speed is incredibly high (see again the manga panels I posted when he is thrown vs when he is flying in the air; see the difference in the inital speed vs the speed when he is approaching the Golem007.jpg&key=57346ba01dfcdb047fd247794667008.jpg&key=9e724979dd51b727bb8de44400bd)

(btw this Golem is about 200m from the waist up where he cuts, so maybe it would be something like on the order of 1 megaton in weight (stone weighs 1,6 tons per m^3, and you imagine compressing his upper body down to a cylinder, I'd say it comes down to maybe 1 or at msot 2 megatons in weight)

Thing is, this feat of cutting the golem and lifting it like that,  people are saying that this is purely due to his own strength; but I'm trying to say here is that (1) Him being thrown with that momentum and (2) there wasn't a huge drag right in front of him because of the Bernouilli's principle which actually reduces the air pressure right above him

There is also the fact that stone is very easy to cut through in fact. Just like this old man is showing us here, if you hammer down on the chisel along a ridge and the stone form cracks that will eventually break the stone in two. This just goes to show that stone can be easily sliced through with enough power, but to actually break through stone with blunt force takes unproportionally more force. The shear strength is closely related to the tensile force, and here is a good example why stone is easier to cut through (compressive force is much higher than the tensile force, and as shown in the video below, that once the cracks forms the material gets significantly weakened) https://www.engineeringtoolbox.com/compression-tension-strength-d_1352.html

Again, you have people want to blow this stone cutting feat out of proportion. With the objections I raised (and therefore I want to check with you guys how you think my arguments make sense) I don't think his stone cutting feat is that much greater (or greater at all) than this feat shown below.

Here the guy has no momentum (unlike Zoro) and just swings around his weapon with one arm, and that creates a shockwave powerful enough to dent a wall made of what could be highly reinforced concrete (some extremely tough material against compression at any rate being that this is a facility that houses radioactive material; and actually the engineering in this world is very much simialr to our own; this is a world government facility and they have technology that is far higher than the civilian world) and he just follows through with the swing casually. He is mortally wounded by the way in this scene, so his actual strength output would be signficantly higher if he was at full health. See how he has put a lot of effort into damaging his opponent, so when he follows through with his swing (with just one arm) he has no momentum or torque, so this all comes to pure arm strength. Again, Zoro slashing through stone is very easy (as shown in the clip) but this is applying compressive force against a material that is extremely tough against compression)

ql4GJJ.gif

 

 

Edited by Kyros

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4 hours ago, Kyros said:

(1) people in this verse are stronger and more durable,  and as such Zoro (at the hgher echelon of superhumans trength) here is durable enough to withstand the heating effects of the air (that would result from what can be seen from the trail of sonic booms as supersonic flight.

As long as you get to explain these phenomena by claiming non-physical attributes (how is durability measured?), trying to apply science is completely meaningless. You also ignore the fact that the air is heating up for a physical reason. Even if an object can survive the heat, an atmosphere is a physical thing to push through. Push fast enough, and everything else near you has to be just as "durable".

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19 minutes ago, Phi for All said:

As long as you get to explain these phenomena by claiming non-physical attributes (how is durability measured?), trying to apply science is completely meaningless. You also ignore the fact that the air is heating up for a physical reason. Even if an object can survive the heat, an atmosphere is a physical thing to push through. Push fast enough, and everything else near you has to be just as "durable".

At which point, I have to post this:

Quote

What would happen if you tried to hit a baseball pitched at 90% the speed of light?

https://what-if.xkcd.com/1/

Spoiler: it doesn't end well

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Posted (edited)

 

5 hours ago, Kyros said:

Just like this old man is showing us here, if you hammer down on the chisel along a ridge and the stone form cracks that will eventually break the stone in two.

The old man cracks a stone, not a stone golem. The golem has the power to move and talk, magical properties that I do not know how they affect the stone's physical properties. If the golem can bend its limbs, how soft is it? Does it crack or does it cut like flesh? How does these magical properties stand against a magical sword? Again:

23 hours ago, Ghideon said:

An analysis from a scientific or physics point of view is not of any use.  

 

After that repetition, let's try another angle at science:

5 hours ago, Kyros said:

I am working under the assumption that the author has insight into and is trying to follow physics as best he can, as he is trying to create a consistent and coherent world, and here the laws of physics aren't different from ours: it's just that the parameters are diferent.

Ok. You just need to provide the mathematical formulas that models the physics in this fantasy world. We need a comparison to the real world laws of physics and the numerical values for parameters, constants or conversion factors etc. With a model we can calculate, simulate and/or predict the outcome of certain events in the fantasy world. In case the parameters are not officially available I guess you can request them from the author. We also need some way to make observations in the fantasy world so that our predictions can be tested.

Note that the above is both a reasonable and realistic request. And maybe also not too far from "real science"; scientists run simulations of real physical events, where sometimes some parameters are unknown or aspects of the real world are not known. Comparisons with observations are made and parameters may be adjusted. Simulations in cosmology is one area of science I think of.

Simplified mathematical models are also quite common when dealing with stone golems and swords. Games such as dungeons & dragons* contains the mathematics of such interactions. Intention is of course to have a balanced game play and a reasonable chance to analyse and predict a situation; do I attack or run? What are the odds that I can take on the golem with my sword? Should I hide and wait for backup? Is the golem immune to magic, should our wizard friend stand back? etc. Again, the creator of the world and/or specific adventure need to provide the numerical parameters required before we can roll the dice and observe the outcome. The "science" aspect of this is that I guess some basic skills of statistics and probabilities are needed to create the world in such a way that it is playable and not an unpredictable random mess. 

For a more physics related example we could use computer games as an analogy. If we would create a Zoro 3rd person action game, what parameters would we feed the physical engine to allow for a fun  game where the stone golem boss is not too hard and not too easy to beat? "Observations" in this case could be the beta testers; does the physics of the world in the game match real physics enough? Expectations of fans of the series? Is the game "fun"? Does authors and other stakeholders approve? And some science: Do we try to be too realistic so the game requires too expensive hardware, limiting the market? What does the latest papers in computer science say; are there any new and novel algorithms that we can use, allowing this game to stand out against the competition? 

As you see there are a few thinks to consider when trying to apply science to the events in the manga. I really understand that such discussions could be quite interesting, for instance among fans that wish to create a fan-made game true to the canon of the series. But it may take some research to get the details needed, can you provide them?

 

*) I'm not that much into such games these days, I think you can have a look at D&D 5th Edition Compendium

 

Edited by Ghideon
spelling

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1 hour ago, Strange said:

At which point, I have to post this:

https://what-if.xkcd.com/1/

Spoiler: it doesn't end well

Nice... +1

------

@Kyros, I don't know how much of a potential manga author or sci-fi author you may be, or would like to be. Sounds like you are interested beyond what regular fiction consumers are.  So here's an idea.

I've always felt very uncomfortable with fiction that tries to explain too much in order to make the story more credible by appealing to standard physics. In my opinion, it defeats the purpose... of entertaining.

But as long as we're talking about fiction, why not invent a whole new physics, or maybe a slightly different physics, in order to justify your story? A fictional physics. You could invent a different biology too, with organisms that have developed or acquired something like fast metabolism and photosynthesis at the same time. They can exploit a very exothermic chemical reaction and also generate their own sugars.

Somebody stop me!

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20 minutes ago, joigus said:

I've always felt very uncomfortable with fiction that tries to explain too much in order to make the story more credible by appealing to standard physics. In my opinion, it defeats the purpose... of entertaining.

I agree. I think the most entertaining are the ones that explain "just enough" to create an internally logical setup. Telling the audience that wormhole technology exists and can be used for travel; ok. Trying to explain wormhole internal functions in terms of quantum mechanics; no thanks. Background information such as how society developed due with the help of wormholes could be ok.
An analogy that I think works; Tolkien created fictive languages for his works and I believe he created extensive linguistic background information. But I don't think he explained the physics allowing the various large creatures, such as dragons, to fly or spit fire. I do not think a section "Physics and the aerodynamic properties of the Fellbeast and its Nazgûl rider" would have been very entertaining. 

I think you also touch on another angle; knowing your audience. Analogy; if an average reader of a certain manga have not yet studied for instance drag and Bernoulli's principle it does not add much value to create a fiction world coherent with both magic and aerodynamics. Let alone explaining all of it to the readers. 
If the background is important and maybe gathers interest from fans that could be published in separate volumes. 

 

38 minutes ago, joigus said:

with organisms that have developed or acquired something like fast metabolism and photosynthesis at the same time.

Cool! Maybe you're writing the plot for a part II of the 1951 Sci-Fi The Thing from Another World? * :-)
I've seen a related idea where (optional) gene manipulation allowed humans to survive for extended periods eating grass and leaf. Good thing for mercenaries on under cover missions on a jungle planet. That author missed the photosynthesis though.

 

44 minutes ago, joigus said:

Somebody stop me!

Why? I want to see pictures of turtles and crabs with photosynthetic shells next 😀

 

*) https://en.wikipedia.org/wiki/The_Thing_from_Another_World, about a malevolent plant-based alien (James Arness). It's based on a novel and other adoptions exists.

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Posted (edited)
5 hours ago, Ghideon said:

The old man cracks a stone, not a stone golem. The golem has the power to move and talk, magical properties that I do not know how they affect the stone's physical properties. If the golem can bend its limbs, how soft is it? Does it crack or does it cut like flesh? How does these magical properties stand against a magical sword? Again:

Yes, I understand that stone is brittle. The golem is actually a normal guy that has gained the ability to absorb, merge and assimilate with as well as control stone. If you can grant that premise, is there any way in which you can have a softer, more flexible core that allows for increased mobility (the stone golem does move increeedibly slow btw) but a harder core of stone (kind of like case hardened steel) jsut by altering its physical and chemical structure jsut a little bit, kind of how like you can make metallic glass that is flexible yet three times as strong as steel? I'm just spitting ideas here

What's important to keep in mind is that this is a series that has been going on for 23 years, now and One Piece is the biggest manga in the world as of now the biggest selling manga in the world. This friday chapter 984 is out! Echiro Oda (the creator) has surely given this way more thought than you'd care to know, and I'm sure he has outside help to counsel him on areas where the science can get sketchy. Just so you know, this guy (Pica) who possess this abiltiy to assimialte with and control stone, the information on him is surprisingly scant, meaning that Oda probably wants to keep the mechanisms of this stone-controlling ability a secret until he divulges it at the proper moment (there are still a lot of unknowns in the story)

Also, call it "magical" sword if you like, but just because you have a concept that is not really conceivable in our world (such as applying hardness to your body or weapon by channeling and applying the equivalence of tchi, ie it's called "haki" in One Piece) does not mean that every scientific law and principle are all topsy turvy. Just because you have this element in the story, does that not mean that the author just doesn't give a shit about how science work?

For instance, it is known in science fiction and other similar genres that most lasers in fiction are not real or provable as real. Often they are supernatural in nature and do not function anywhere close to how real light should. Therefore, lasers/light beams are only accepted as real if they meet, at a minimum, a few of these criteria:
 

  • The beam refracts in a new material, such as a liquid or...
  • The beam reflects off a material that it can be expected to, such as a non-magical mirror
  • The beam is called lightspeed by reliable sources
  • It is stated to be made of photons or light itself, again by a reliable source
  • It has its origin at a realistic source of light, such as a camera

Furthermore, there are a few criteria which show a beam is NOT real light:
 

  • It is shown at different speeds in the same material
  • It is tangible and can be interacted with physically by normal humans
  • They do not travel in straight lines (unless you can prove refraction/reflection)

In several science fiction
- The Lazers were never said to move at light speed
- True light can be reflected.
- They create explosions thus interacting with people.

 

 

6 hours ago, Phi for All said:

As long as you get to explain these phenomena by claiming non-physical attributes (how is durability measured?), trying to apply science is completely meaningless. You also ignore the fact that the air is heating up for a physical reason. Even if an object can survive the heat, an atmosphere is a physical thing to push through. Push fast enough, and everything else near you has to be just as "durable".

Here are examples of sonic booms and I don't know what you're getting at. Doesn't the manga author display the sonic boombs such as this and why is it so different? Zoro is durable enough to withstand it apparently (though I'm actually curious as to how the heating effects build up differently to the titanium or other metal that has higher thermal conductivity)

 

Edited by Kyros

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Posted (edited)
49 minutes ago, Kyros said:

Also, call it "magical" sword if you like, but just because you have a concept that is not really conceivable in our world (such as applying hardness to your body or weapon by channeling and applying the equivalence of tchi, ie it's called "haki" in One Piece) does not mean that every scientific law and principle are all topsy turvy. 

You asked for a physical analysis and I choose the word "magic" for the things that seems to contradict the physics in the real world. You are free to provide a list of the proper definitions and terms to use. 

49 minutes ago, Kyros said:

Just because you have this element in the story, does that not mean that the author just doesn't give a shit about how science work?

No. It means that the mainstream science of the real world have no predictive power and is not useful to explain the magical events in his creations. 

 

48 minutes ago, Kyros said:

If you can grant that premise, is there any way in which you can have a softer, more flexible core that allows for increased mobility (the stone golem does move increeedibly slow btw) but a harder core of stone (kind of like case hardened steel) jsut by altering its physical and chemical structure jsut a little bit, kind of how like you can make metallic glass that is flexible yet three times as strong as steel?

Yes, I can create various kinds of flexible and hard constructions out of stone. But they would not possess intelligence, move by free will and talk as in the manga.  I would have to visit Pica and press him on the source of the knowledge he possess. Unfortunately Pica is a work of fiction,  my skills from the real world does not explain the results of his abilities in the manga.

 

49 minutes ago, Kyros said:

the stone golem does move increeedibly slow btw

Ok. Then the author seems to have made mistakes in the frames you posted:
- The golem seems to look down, in the direction of the approaching Zoro. That is not possible if the golem is moving incredibly slow.
- The golem seems to talk, that means some part of it moves fast enough to move air at a frequency the others could hear.

Or it could mean that the author did not intend the story to make sense physically. The author maybe wanted to create entertaining scenarios. 

 

49 minutes ago, Kyros said:

What's important to keep in mind is that this is a series that has been going on for 23 years, now and One Piece is the biggest manga in the world as of now the biggest selling manga in the world.

That implies that mr Echiro Oda creates excellent* and entertaining manga. It does not say much how to apply science to explain or predict outcome in his work of fiction.

 

49 minutes ago, Kyros said:

Just so you know, this guy (Pica) who possess this abiltiy to assimialte with and control stone, the information on him is surprisingly scant, meaning that Oda probably wants to keep the mechanisms of this stone-controlling ability a secret until he divulges it at the proper moment (there are still a lot of unknowns in the story)

Thanks, yet another confirmation of

On 6/30/2020 at 4:21 PM, Ghideon said:

An analysis from a scientific or physics point of view is not of any use.  

Conjecture**: For every explanation from the fiction world there will be an equal and opposite counter-explanation from the real world telling how physics does not apply. The result is zero; no new knowledge about the events from a scientific point of view.

I'll leave to the interested reader to provide evidence and a model.

 

*) (maybe worth taking a closer look?)

**) Ghideon's third law of motion in magical related fiction (?) I guess we get the first two later in this thread if it remains open.

 

Edited by Ghideon
added missing section

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1 hour ago, Ghideon said:

I agree. I think the most entertaining are the ones that explain "just enough" to create an internally logical setup.

Exactly. To me that's just about how much I need. Nothing too far-fetched, nothing too ridiculously absurd or out of proportion. And a couple of semi-justifications when needed --mostly because it would be shocking or surprising otherwise.

 

1 hour ago, Ghideon said:

Cool! Maybe you're writing the plot for a part II of the 1951 Sci-Fi The Thing from Another World? * :-)
I've seen a related idea where (optional) gene manipulation allowed humans to survive for extended periods eating grass and leaf. Good thing for mercenaries on under cover missions on a jungle planet. That author missed the photosynthesis though.

+1. :D :D 

Maybe some brainstorming of ideas for a sci-fi story on The Lounge could be possible. Somehow I don't see myself as a writer, though. I can't think of a simple narrative. Almost everything I can come up with is a variation of something I've read or watched. :( 

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56 minutes ago, joigus said:

Exactly. To me that's just about how much I need. Nothing too far-fetched, nothing too ridiculously absurd or out of proportion. And a couple of semi-justifications when needed --mostly because it would be shocking or surprising otherwise.

 

+1. :D :D 

Maybe some brainstorming of ideas for a sci-fi story on The Lounge could be possible. Somehow I don't see myself as a writer, though. I can't think of a simple narrative. Almost everything I can come up with is a variation of something I've read or watched. :( 

Just help me out in a purely hypothetical, how do we measure the cutting force? Like when he cuts the golem like this vertically (lets start with that)011.jpg&key=b4ee114be2d5a3daca0b045349f7

Do I have to take the shear modulus of stone into account here? It's not so easy so as to just say depth * length of the cut times the shear modulus (or shear strength) as the stone actually behaves differently once you've breached the shear strength, due to it being a crystalline material, when Zoro here applies an air projectile, when he breaches the shear strength of the stone, the cracks finds its way through the structure (same way a heated stone that rapidly cools down easily ruptures being that the cracks finds the "easiest way" through the crystals that the stone is composed of) and the stone gets significantly weakened by this. (same way the old guy can crack a stone in two with the chisel and how this is done in construction and stuff all the time with bigger boulders).

@Ghideonyeah  Pica somehow makes the stone more malleable and ductile as a softer core underneath to allow for his Golem to move, and supposing as Pica actually controls stone, that he can assimilate stone that is deeper underneath the crust where it's more pliable and ductile, he can assimilat this and make this as his flexors and tensors underneath the hard exsterior stone surface. That's just a suggestion (I'm sure Oda has some exemplary explanation for this lol and I'll get back to you when he does)

But regardless of all of that, how would you calculate the cutting force? What way would you go about it supposing this was a real world scenario?

I'm pretty much learning this stuff on the fly btw bc of "sheer" interest and I'm finding it to be veery interesting! Anyway, the shear modulus is usually something like 1/3 of the young's modulus, and the young's modulus is the thing we use to measure linear and normal forces (the act of cutting is a shear force). I don't know how exactly how much weaker a stone would get after you breach the shear stress of the stone, but from judging by several videos, such as this, my idea is that stone is jsut inherently weak to cuts.

 

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9 hours ago, Ghideon said:

The old man cracks a stone, not a stone golem. The golem has the power to move and talk, magical properties that I do not know how they affect the stone's physical properties. If the golem can bend its limbs, how soft is it? Does it crack or does it cut like flesh? How does these magical properties stand against a magical sword? Again:

Btw this is an island in the middle of the ocean somewhere, so the stone is limestone most probably (just humour me here). So as such, it is more malleabe in fact. It's not as hard as other stones (ie easy to carve) so let's for the sake of argument say he uses soft and relatively malleable limestone for his flexors and tensors to move around, while having a harder stone exterior...?

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Posted (edited)
19 hours ago, Kyros said:

the stone is limestone most probably (just humour me here)

Ok. Let's pretend for this post the stone golem has limestone properties. We throw person at nearly the speed of sound against a limestone figure several hundred meters tall. The effect is similar to a bug on a windshield: "splat". 
The information you provide does not help: the physics of the real world lacks predictive power in the fiction world of Zoro. 
 

Edited by Ghideon
grammar

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On 7/2/2020 at 9:38 PM, Ghideon said:

Ok. Let's pretend for this post the stone golem has limestone properties. We throw person at nearly the speed of sound against a limestone figure several hundred meters tall. The effect is similar to a bug on a windshield: "splat". 
The information you provide does not help: the physics of the real world lacks predictive power in the fiction world of Zoro. 
 

How do you calculate cutting force though? From a purely hypothetical point of view

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Posted (edited)
On 7/6/2020 at 11:56 AM, Kyros said:

How do you calculate cutting force though? From a purely hypothetical point of view

I think you have missed the point in previous posts: Since science does not apply to the described situation is would not be very scientific to provide a response. I believe that's an important part of science (or, more applicable in my case, engineering) to realise when and why the models do or don't apply; the data is insufficient or the question asked does not have an answer. In this case with a cartoon about magical beings modifying the situation until science is applicable would result in a hypothetical situation having very little (or zero) in common with the fiction in the cartoon.

That said, let's provide an "answer" anyway, maybe the reasoning below will provide some insights why the question is rather pointless in science.

Initial question: Hypothetically, what force is required by a fiction hero to cut through a thick magical stone golem with a magically powered sword when the hero is flying at nearly supersonic speed?

The objects in the question above does not exist so we change the question to a hypothetically real scenario: What force is required to cut through a stone with sword when the individual holding the sword is flying at high speed?

Observation: stone is not cut by slicing through it with a handheld tool like knife through clay. Cutting* stone requires, AFAIK, sawing or rotating motion using a suitable tool such as a diamond saw blade. So the individual holding the tool can’t be moving at speed relative to the stone, they need to be in reaching distance of the stone for the time it takes to cut (or saw). The stone in this case is very thick, but applying excessive force is of no use. You can’t cut much faster; the tool will overheat and/or stop rotating and/or break. This means that the thickness of the stone does not affect the force to use. The thickness affects the time it takes to cut through. I do not have specifications for stone cutting tools available so I’ll go by experience. The force used when cutting should be of same magnitude as the weight of the handheld tool; do not force down a disc cutter with your body weight. This means the question actually is: What force is required to cut through a stone with an applicable handheld tool? A reasonable, but highly approximate answer, is: 100 Newton.

The follow up question in the context of the manga scene would then be: How long would it take to cut through an approximately 100 m thick stone cylinder using handheld tools such as a disc cutter fitted with a diamond blade? Answer: Who cares? At least much longer than what seems to be the case in the fiction cartoon meaning that engineering and science seems to be unable to provide an answer to the original hypothetical question. "Force" is not a useful concept.

Final notes: all the above is no way near the situation in the drawings. The stone does not seem to be cut by the hero, it seems to be split. The sword is not important, it is the indestructible hero smashing through the stone as a projectile that does the trick. "Momentum" may be applicable. I'm not going to do any analysis but I guess @Strange provided an answer above in scienceforums.net...comment-1146385

*) Splitting a stone is another thing. But the question is about cutting, not splitting.

 

Edited by Ghideon

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22 minutes ago, Ghideon said:

I think you have missed the point in previous posts: Since science does not apply to the described situation is would not be very scientific to provide a response. I believe that's an important part of science (or, more applicable in my case, engineering) to realise when and why the models do or don't apply; the data is insufficient or the question asked does not have an answer. In this case with a cartoon about magical beings modifying the situation until science is applicable would result in a hypothetical situation having very little (or zero) in common with the fiction in the cartoon.

That said, let's provide an "answer" anyway, maybe the reasoning below will provide some insights why the question is rather pointless in science.

Initial question: Hypothetically, what force is required by a fiction hero to cut through a thick magical stone golem with a magically powered sword when the hero is flying at nearly supersonic speed?

The objects in the question above does not exist so we change the question to a hypothetically real scenario: What force is required to cut through a stone with sword when the individual holding the sword is flying at high speed?

Observation: stone is not cut by slicing through it with a handheld tool like knife through clay. Cutting* stone requires, AFAIK, sawing or rotating motion using a suitable tool such as a diamond saw blade. So the individual holding the tool can’t be moving at speed relative to the stone, they need to be in reaching distance of the stone for the time it takes to cut (or saw). The stone in this case is very thick, but applying excessive force is of no use. You can’t cut much faster; the tool will overheat and/or stop rotating and/or break. This means that the thickness of the stone does not affect the force to use. The thickness affects the time it takes to cut through. I do not have specifications for stone cutting tools available so I’ll go by experience. The force used when cutting should be of same magnitude as the weight of the handheld tool; do not force down a disc cutter with your body weight. This means the question actually is: What force is required to cut through a stone with an applicable handheld tool? A reasonable, but highly approximate answer, is: 100 Newton.

The follow up question in the context of the manga scene would then be: How long would it take to cut through an approximately 100 m thick stone cylinder using handheld tools such as a disc cutter fitted with a diamond blade? Answer: Who cares? At least much longer than what seems to be the case in the fiction cartoon meaning that engineering and science seems to be unable to provide an answer to the original hypothetical question. "Force" is not a useful concept.

Final notes: all the above is no way near the situation in the drawings. The stone does not seem to be cut by the hero, it seems to be split. The sword is not important, it is the indestructible hero smashing through the stone as a projectile that does the trick. "Momentum" may be applicable. I'm not going to do any analysis but I guess @Strange provided an answer above in scienceforums.net...comment-1146385

*) Splitting a stone is another thing. But the question is about cutting, not splitting.

 

Yes, the whole point of fantasy is that it allows one to conceive of ideas that real life doesn't allow. Questions like this OP in a scientific context  are not useful because they require the suspension of scientific rigour.

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