Need help with physics in story

[bakura_fan]

Not sure if this is where it should go, but I've run into a snag in my story. So, the main character is a fairy that is being trained to fullfill his destiny as his tribes chosen one. This means he can become human at will. First, he has to be trained to get around, without flying. So, here's my question. If a 7-9 inch being, becomes a 5' 6" - 6' being, is there any difference in gravity that would be noticable. So far he's being trained on a small scale, so when he gets bigger he can continue to train on the same scale as he was when he was small. So...ok...uhm. yeah. hope I made sense. and try and use simple sentences for me...I've never been able to understand really complex things. Thanks!

Oh, and I know that this being a fantasy story I can make gravity do whatever, but I'm trying to make the world with the same logics, or close to the same, that we have in this world. again, thanks!

[Dante]

No noticable difference in gravity, all objects of these orders of magnitude will continue to experience a near earth gravitational acceleration of 9.80665 m/s^2, or... given that you like those EVIL English units, 32 ft/sec. That being said...

There would be a major difference in the terminal velocities they would experience. Given that a full grown person weighs more they can generally attain a higher terminal velocity then say a cricket. Because of this, a cricket could survive being dropped from the empire state building... a person could not. In the end, this means that he would have to do more to battle wind resistance or could jump from objects of a larger scale. (Drop a cricket from your kitchen table... now try a human off an object of similiar scale difference... or maybe not). (EDIT, maybe a lovebird with its wings clipped is a better example )

Other than this, there are a few other variations, for instance water acts somewhat differently for his scale then ours. (Perhaps surface tension would be a noticable effect)... Overall though the physical differences are relatively small... next time come back to use with a character whose size is on the order of half an angstrom... then we can talk .

[bakura_fan]

No noticable difference in gravity, all objects of these orders of magnitude will continue to experience a near earth gravitational acceleration of 9.80665 m/s^2, or... given that you like those EVIL English units, 32 ft/sec. That being said...

I don't comprehend much math like that unfortunately. =_=

so, if he was trained with rocks as weights, then as a human with armor equaling roughly the same as the rocks were to him, there'd be no real difference?

There would be a major difference in the terminal velocities they would experience. Given that a full grown person weighs more they can generally attain a higher terminal velocity then say a cricket. Because of this, a cricket could survive being dropped from the empire state building... a person could not. In the end, this means that he would have to do more to battle wind resistance or could jump from objects of a larger scale. (Drop a cricket from your kitchen table... now try a human off an object of similiar scale difference... or maybe not). (EDIT, maybe a lovebird with its wings clipped is a better example )

ok. uhm. don't think he's ever had to deal with this due to his wings...also, I'm hoping he doesn't fall (my story's kinda writing itself at times. I intend to keep someone alive, they end up dead...not major characters luckily.)
So, jumping. hmm. it would be harder to jump for him at a bigger scale than smaller? (like same scale set up?)

Other than this, there are a few other variations, for instance water acts somewhat differently for his scale then ours. (Perhaps surface tension would be a noticable effect)... Overall though the physical differences are relatively small... next time come back to use with a character whose size is on the order of half an angstrom... then we can talk .

oh. water. that might be a good thing to note. dang. (thinks of the few water scenes *washing dishes, fetching water from the lake*) How would that be different on his scale, anything big?

what's an angstrom?

[Dante]

ok. uhm. don't think he's ever had to deal with this due to his wings...also, I'm hoping he doesn't fall (my story's kinda writing itself at times. I intend to keep someone alive, they end up dead...not major characters luckily.)
So, jumping. hmm. it would be harder to jump for him at a bigger scale than smaller? (like same scale set up?)

If he trains with rocks as weights... we... can't tell how much he can lift given that muscle mass is a function of the magical spell of hapiness and not physics . If you can change his size between being a fairy and being a human it would make sense that you've also changed his muscle mass... (despite the fact that this alone violates conservation of mass XD).

ok. uhm. don't think he's ever had to deal with this due to his wings...also, I'm hoping he doesn't fall (my story's kinda writing itself at times. I intend to keep someone alive, they end up dead...not major characters luckily.)
So, jumping. hmm. it would be harder to jump for him at a bigger scale than smaller? (like same scale set up?)

Nope, wings make it more apparent... think parachute, he doesn't even have to flap them when he wants to land, just extend them to increase his surface area and his speed reduces to a level that makes landing comfortable (although if he doesn't extend his wings he should still be able to land albeit slightly rougher).

oh. water. that might be a good thing to note. dang. (thinks of the few water scenes *washing dishes, fetching water from the lake*) How would that be different on his scale, anything big?

Can't really tell how different it would be, he definitely would have the power to overcome surface tension, I mean there are plenty of amphibous animals out there. But it might "feel" different at that size given that water would apply a force to him. He's not small enough to say, walk on water (like some creatures can, check out a paper wasp ) but he would feel some of the tug from the effect.

what's an angstrom?

Two hydrogen atoms side by side.

[bakura_fan]

If he trains with rocks as weights... we... can't tell how much he can lift given that muscle mass is a function of the magical spell of hapiness and not physics . If you can change his size between being a fairy and being a human it would make sense that you've also changed his muscle mass... (despite the fact that this alone violates conservation of mass XD).

hehheh. Sorry. So, I'll try not to get too deep into that aspect. It's already making my head hurt.

Nope, wings make it more apparent... think parachute, he doesn't even have to flap them when he wants to land, just extend them to increase his surface area and his speed reduces to a level that makes landing comfortable (although if he doesn't extend his wings he should still be able to land albeit slightly rougher).

ok. gotcha. understood.

Can't really tell how different it would be, he definitely would have the power to overcome surface tension, I mean there are plenty of amphibous animals out there. But it might "feel" different at that size given that water would apply a force to him. He's not small enough to say, walk on water (like some creatures can, check out a paper wasp ) but he would feel some of the tug from the effect.

hmm. ok. not sure if it's too necessary to the story, but maybe if I drew it or it became a movie *shrugs*

Two hydrogen atoms side by side.

ah...yeah...that's a tad too small for me.

[Dante]

actually I'm wrong, the radius of a hydrogen atom is 1/2 an angstrom so that an actual angstrom is a diameter of one angstrom.

aka, while it doesn't matter an angstrom is the width of a hydrogen atom...

[minakichan]

Yeah, I think that considering that you've already broken conservation of mass and energy, does it really matter anymore? ^_^

But I do like that you're at least TRYING to be physically correct >_>;

[EricTheFred]

First of all... Pascal? An angstrom is 1/10th of a nanometer. The atomic radius of Hydrogen is 25 picometers. That's 1/4 of an angstrom. You were right the first time.

Of course, the width of an atom is subject to its energy state, ionization, etc. etc. so it's kind of arbitrary.

Bakura fan, the 'physics' really depend upon what your growth methodology is. I do sympathize with this, by the way. I almost always try to establish rules when I introduce fantastic elements. They may not operate by our physics, but there is some other physics to which they must still adhere. Keeps it from feeling like hand-waving or deus ex machina.

So, the question is, how does your fairy grow? If we assume that the growth causes him to become biologically equivalent to a human (let's say whatever makes him a fairy isn't a physical thing. He doesn't lose this quality, or the ability to go back, but his body chemically changes from original to morph.) In this case, he shouldn't be physically capable of unreasonable feats of strength (unless by application of additional magic), but he may or may not have an adjustment process to go through to deal with the different relationship of weight and size of objects in the human-scale world (as objects increase in size, their dimensions grow linearly, but their weight exponentially.)

Or, he may be 'magnified', literally scaled up from his normal much smaller self down to his very quarks. In this case, you have a number of things to work out.

1) Does he breath oxygen? If so, how? Perhaps magic magnifies and demagnifies the atoms as his lungs draw them into his bloodstream. Or perhaps he isn't made of physical atoms like a human, but instead of such stuff that dreams are made of, and he only draws breath in order to talk. He has issues like food and water to figure out, as well.

2) Does his weight change? If he is magnified, is he still the same weight? I have a fairy character in a young adult series I'm developing who can vary from three inches tall to size of a middle-school student (which is what she normally appears as in our world.) Her physical self is the smallest size. She doesn't change weight when she magnifies, so she has to apply downward force with her magic to keep her feet on the ground in a wind.

3) One gain from magnification: ants can lift so much because of strength of materials differences. The reason no insect could be the size of a horse is that their exoskeletal frame can't handle the load. Bones can work at a much larger scale than chitin. But if he's magnified, his effective strength, including the force his body can stand, must be magnified as well (or he wouldn't be able to deal with atmospheric pressure, much less the world around him.) so perhaps he, like an ant, can easily lift many times his own weight over his head, and survive that fall from the Empire State Building with ease.

[Dante]

First of all... Pascal? An angstrom is 1/10th of a nanometer. The atomic radius of Hydrogen is 25 picometers. That's 1/4 of an angstrom. You were right the first time.

Of course, the width of an atom is subject to its energy state, ionization, etc. etc. so it's kind of arbitrary.

No no no... I have it memorized as half an angstrom... Hmm... that's why ... mine is the "calculated" atomic radius while yours would be the measured.

http://en.wikipedia.org/wiki/Hydrogen

Meh... I always was a theorist. ITS HALF AN ANGSTROM I SAY!!!! YOU'LL PRY AWAY THE QUARTER OF AN EXTRA ANGSTROM WHEN YE PRY IT OUT OF ME COLD DEAD HANDS!!!

[bakura_fan]

Bakura fan, the 'physics' really depend upon what your growth methodology is. I do sympathize with this, by the way. I almost always try to establish rules when I introduce fantastic elements. They may not operate by our physics, but there is some other physics to which they must still adhere. Keeps it from feeling like hand-waving or deus ex machina.

So, the question is, how does your fairy grow? If we assume that the growth causes him to become biologically equivalent to a human (let's say whatever makes him a fairy isn't a physical thing. He doesn't lose this quality, or the ability to go back, but his body chemically changes from original to morph.) In this case, he shouldn't be physically capable of unreasonable feats of strength (unless by application of additional magic), but he may or may not have an adjustment process to go through to deal with the different relationship of weight and size of objects in the human-scale world (as objects increase in size, their dimensions grow linearly, but their weight exponentially.)

Or, he may be 'magnified', literally scaled up from his normal much smaller self down to his very quarks. In this case, you have a number of things to work out.

1) Does he breath oxygen? If so, how? Perhaps magic magnifies and demagnifies the atoms as his lungs draw them into his bloodstream. Or perhaps he isn't made of physical atoms like a human, but instead of such stuff that dreams are made of, and he only draws breath in order to talk. He has issues like food and water to figure out, as well.

2) Does his weight change? If he is magnified, is he still the same weight? I have a fairy character in a young adult series I'm developing who can vary from three inches tall to size of a middle-school student (which is what she normally appears as in our world.) Her physical self is the smallest size. She doesn't change weight when she magnifies, so she has to apply downward force with her magic to keep her feet on the ground in a wind.

3) One gain from magnification: ants can lift so much because of strength of materials differences. The reason no insect could be the size of a horse is that their exoskeletal frame can't handle the load. Bones can work at a much larger scale than chitin. But if he's magnified, his effective strength, including the force his body can stand, must be magnified as well (or he wouldn't be able to deal with atmospheric pressure, much less the world around him.) so perhaps he, like an ant, can easily lift many times his own weight over his head, and survive that fall from the Empire State Building with ease.

In my story. Fairy's are just like little people, just with a better understanding of magic and alchemy. Their physical structure is the same. So, I guess when I envisioned (sp?) him changing, he would grow bigger, and lose his magic ability's (also his wings of course). So. I guess think of those superheros who can grow small and grow big? I guess that's how it is. There really isn't too much different in our world than there's (except for magic and mythical creatures ).

Edit: i guess the big thing I want is to make any training he goes through sound reasonable. First he trains, then he gains the power to transform (which takes a few months to accomplish a full transformation), then onto more physical training, then swordfighting and the like. Right now he's being trained to build up his muscles in his arms and legs (since fairies rarely use them the way humans do.) I want to make sure that it's not going to be in vain when he does become fully human. eh. I'm probably thinking too much on this. =_=;

Edit...again: I should probably clarify something. when I say fairies it's not like the itty bitty teeny weenie things. He stands a good 9-10 inches. does that make a difference for those things? (getting headache.) I never liked physics and such. bleh.

[Dante]

If you can get him to grow small enough, then he can gain the power to quantum tunnel and pass through entire walls... however he will in doing so lose a definite position and/or momentum until someone or something collapses his wavefuntion... which could be very awkward should he be discovered halfway between one room and another. X_x

[bakura_fan]

If you can get him to grow small enough, then he can gain the power to quantum tunnel and pass through entire walls... however he will in doing so lose a definite position and/or momentum until someone or something collapses his wavefuntion... which could be very awkward should he be discovered halfway between one room and another. X_x

....he grows...doesn't shrink. and you're comment just made my head hurt (was serious when I said I know nothing...X_X bleh.)

[EricTheFred]

No no no... I have it memorized as half an angstrom... Hmm... that's why ... mine is the "calculated" atomic radius while yours would be the measured.

http://en.wikipedia.org/wiki/Hydrogen

Meh... I always was a theorist. ITS HALF AN ANGSTROM I SAY!!!! YOU'LL PRY AWAY THE QUARTER OF AN EXTRA ANGSTROM WHEN YE PRY IT OUT OF ME COLD DEAD HANDS!!!

But if those hands are close enough to absolute zero, it'll be at the ground state...

If you can get him to grow small enough, then he can gain the power to quantum tunnel and pass through entire walls... however he will in doing so lose a definite position and/or momentum until someone or something collapses his wavefuntion... which could be very awkward should he be discovered halfway between one room and another. X_x

Hmm... this introduces a whole new dimension to Heisenberg. Does he count as his own observer? Or is his presence on one side or the other of the wall arbitrary until a third party gets involved?

[Dante]

No no no... you're missing the point, the particle doesn't HAVE such a thing as a definite position or moment, nor can an electron have for instance a preferential political party!

[EricTheFred]

But... if it has no definite position, how can there be a point to miss?

[Dante]

Exactly, which is precisely why you keep missing my point .

[termyt]

Allow me to answer simply.

Generally speaking, it's safe to ignore physics in this case. In fiction when things change size, it's safe to assume that everything remains proportional.

If he can do the normal things a fairy can do, then he can do the normal things a human can do when he grows to human size.

The only reason to place limitations on this would be for your own story development. For example, perhaps the change in size makes him a little more clumsy for a while. Perhaps being small requires greater balance, so he is a lot more agile. Or, like an ant, perhaps he is proportionally stronger than a normal human so he is extra strong. Perhaps muscle mass does not transfer well during the size change, so he is weaker. It can go either way.

I don't think you need to take any extra considerations into account to keep the laws of physics. The important thing to keep in mind is that the changes should be uniform for anyone who undergoes the transformation. If it makes one fairy weaker, it should make them all weaker. (Although you could introduce a plot device that alters the effects for different fairies - like the type of training they go through, their own genetics, or close proximity of a catalyst, etc. Even this could be reasonably explained as "it affects different fairies different ways" if you did not want to go into detail.)

I hope that helps.

[bakura_fan]

Allow me to answer simply.

Generally speaking, it's safe to ignore physics in this case. In fiction when things change size, it's safe to assume that everything remains proportional.

If he can do the normal things a fairy can do, then he can do the normal things a human can do when he grows to human size.

The only reason to place limitations on this would be for your own story development. For example, perhaps the change in size makes him a little more clumsy for a while. Perhaps being small requires greater balance, so he is a lot more agile. Or, like an ant, perhaps he is proportionally stronger than a normal human so he is extra strong. Perhaps muscle mass does not transfer well during the size change, so he is weaker. It can go either way.

I don't think you need to take any extra considerations into account to keep the laws of physics. The important thing to keep in mind is that the changes should be uniform for anyone who undergoes the transformation. If it makes one fairy weaker, it should make them all weaker. (Although you could introduce a plot device that alters the effects for different fairies - like the type of training they go through, their own genetics, or close proximity of a catalyst, etc. Even this could be reasonably explained as "it affects different fairies different ways" if you did not want to go into detail.)

I hope that helps.

actually, that helps alot, thanks.