[deleted]

If it's ZUN, then they're the ones who are doomed.

Try outs for joining Nanoha's Time Space Administration Bureau.

Making friends
one at a time

wait, whats up with the Shanghai shooting stars along with Marisa?

Alice is her partner

$20 on them firing at U.S.

Is that American, Canadian, or Australian dollars?

excuse me, how do you spell overkill... did I do it right?

This is confusing the more I think about it. They are flying. Since the ground is drawn at the top, you can tell that they are firing away from the world. However, that would mean that Marisa is flying her broom above herself, meaning she's flying upside-down. Now that's fine, seeing how she can fly her broom however she wants to. I'm pretty sure after a few years you can learn to do that.

But then there's the physics. At first, I thought that the dragging color was just cool photoshop effects to add intensity to the scene. But, it's really motion blur. They are flying up. You can tell because Marisa's broom is bent towards the direction of the world, meaning they were going up THAT FAST.

And what's more ridiculous is that she is still going in that direction while firing beams of something that I would think would cause recoil. But no, she's still going forward while firing Master Sparks while kickflipping off of a broom in the sky.

UPSIDE DOWN.

However, after writing all of this I realize that she's able to keep her broom in one position in the air and tied her arm to it with a rope so that she doesn't blast herself down to earth from the recoil.

I just don't feel like erasing all of that.

Nilix, I just realized that yes, they have the Earth "above" them, and because of that, I can only think of New Moon War, or at least stopping actual UFO's

Lavos was going to attack... Was.

Firing energy does not produce much recoil at all. The mass of energy is m = E/c^2 which is very very light. The energy would heat up the air in front of them and create a shock wave backwards, meaning they are being pushed towards the ground, not flying away from it. The blur lines are probably caused by refraction due to heated air.

My money is on the Watasuki sisters or they're stopping a meteor.
The pic is upside down they're actually firing up see the ground in the upper right corner.
Marisa has this if we fail we're all going to die look on her face.

That's obvious. They let Flandre out of the house.

Okay this deserves the epic tag. Thinking of creating a new tag or pool called "Beamspam"

Nosaji, that would be the "danmaku" tag

unicode said:
Firing energy does not produce much recoil at all. The mass of energy is m = E/c^2 which is very very light. The energy would heat up the air in front of them and create a shock wave backwards, meaning they are being pushed towards the ground, not flying away from it. The blur lines are probably caused by refraction due to heated air.

apfsds@!#R!#$

E=mc^2 doesn't relate to kinematics, it relates to converting mass into energy. The kinetic energy of a particle is still 1/2mv^2, and the momentum of these energy beam mahou shoujo systems are still going to be m*v.

Do not attempt to kill catgirls at a greater rate than me, mah boy. This ain't worth talking about, so don't bring it up.

It looks cool, she is powerful.

If she shot an energy particle that weighs a metric ton at Rinnousuke's crotch, then that's 1000kg going like 800 m/s which is one to several times the speed of sound in most atmospheres... So say she's a 50 kg shoujo. We're going to need to do mv=mv to conserve momentum in this system. 800*1000 = 50*v 800000/50 which gives us a little girl that wants to go flying backward at 16000 m/s. So 1/2mv^2 again to give us the energy, to give us the acceleration of that to give us the force she needs to exert to counteract it...

16000^2 ... (2^4*10^2)^2... 2^8*10^4*50kg/2

2^8*10^4*25 = holyshit joules. the energy she needs to counteract to maintain her momentum...

annnd fuckit, I forget how to figure out instantaneous acceleration in these systems. I never understood how it could be anything except infinite. She's got plenty of force to recoil against unless her weapon itself is useless.

Dr_Fine_Rolo said:
E=mc^2 doesn't relate to kinematics, it relates to converting mass into energy. The kinetic energy of a particle is still 1/2mv^2, and the momentum of these energy beam mahou shoujo systems are still going to be m*v.

Photons are massless; you want to use E=pc to calculate the momentum of the energy beam. Using conservation of linear momentum we get γmv=E/c, and solving yields v=c(E/(E^2+c^4*m^2)^1/2). As a sanity check note as E->∞ v->c.

In any case, you need relativistic kinematics to treat this problem since photons are involved.

Dr_Fine_Rolo said:
annnd fuckit, I forget how to figure out instantaneous acceleration in these systems. I never understood how it could be anything except infinite.

Conservation of momentum just gives you the final state of the system; it doesn't tell you the time it takes to reach that state. I think you're getting an infinite acceleration from assuming that the velocity change is instantaneous.

They're trying to destroy that blasted Soccer Ball, only to find out it's still intact.

CRAW said:
Mannosuke removed his loin cloth again.

Holy hell, did they make it? was it over?

freefunctor: I did notice that there would be relativistic work I really didn't want to look up so I dropped things to merely newtonian levels with my 800m/s.

tldr;
The recoil incurred by the mahou shoujo is proportional to the damage her beam is doing. If there's no recoil, it's not doing a lot of damage.

I did get the acceleration thing at one point in physics, but I've forgotten by now and my notes are locked up.

[deleted]

Sorry for writing after the end, but I want to clarify a concept.
Recoil is the transfer of momentum from the projectile (energy in this case) to the shooter. I did not calculate it but this momentum should be negligible, otherwise everything around would have vaporized.
E=mc^2 relates mass to energy, but mass and energy do not convert into each other. Energy has mass. Consider a closed system of 2 hydrogen atoms, when they fuse into a helium atom they give out energy. The mass of the helium atom is less than the mass of the two original hydrogen atoms. By the conservation of mass, the energy that has been released must have a certain mass to account for the difference.

RNGCombo said:
If it's ZUN, then they're the ones who are doomed.

Not if they're blasting him with artistic talent! Zing!

slockhart916 said:
Not if they're blasting him with artistic talent! Zing!

That was less of a 'zing!' and more of a slow, low-pitched 'hurrrrr'.

XD I lol'd at those physics calculations!
Isn't that magic, after all?

unicode said:
E=mc^2 relates mass to energy, but mass and energy do not convert into each other. Energy has mass. Consider a closed system of 2 hydrogen atoms, when they fuse into a helium atom they give out energy. The mass of the helium atom is less than the mass of the two original hydrogen atoms. By the conservation of mass, the energy that has been released must have a certain mass to account for the difference.

"Conservation of mass and energy

The concept of mass–energy equivalence unites the concepts of conservation of mass and conservation of energy, allowing rest mass to be converted to other forms of energy, like kinetic energy, heat, or light. Kinetic energy or light can also be converted to particles which have mass. The total amount of mass–energy in a closed system remains constant because energy cannot be created or destroyed and, in all of its forms, trapped energy has mass. According to the theory of relativity, mass and energy as commonly understood are two names for the same thing, and one is not changed to the other. Rather, neither one appears without the other. When energy changes type and leaves a system, it takes its mass with it."

Recoil is the transfer of momentum from the projectile (energy in this case) to the shooter. I did not calculate it but this momentum should be negligible, otherwise everything around would have vaporized.

I have never seen evidence in anime that energy beams actually travel the speed of light, or anything near it. A lot of the time they seem to sub-sonic, moving almost as fast as an arrow. Because it looks cool, and I did calculate for that, and she has a whole lot of work to do. She needs to be creating thousands of newtons of force to keep herself neutral in the system.

Even if this was a beam of photons, or something else travelling near light speed, it would have significant recoil. This energy beam has a lot photons in it, a lot energy, and it's going the speed of light. It has enough photons and energy and radiation that we can see it from the side. That means the particles are bumping into each other and radiating out of the one direction of the ray and hitting our eyes.

Because it's energy it has no significant momentum? Tell that to Hiroshima or Nagasaki. The laser in your physics class has no momentum because it's putting out a max of like 80 joules. My .22 doesn't have any recoil either.

Killing over 9000 cat girls a second here.

Dr Fine Rolo said:
mass and energy as commonly understood are two names for the same thing, and one is not changed to the other

This is exactly what I meant.

I give it that since the beams are subsonic, they must be particles and not light. However the energy potential of such a stream of energy is immense without necessarily producing much recoil.

Take a machine gun which fires 5-gram bullets at a rate of 500 bullets per minute. Every minute it shoots 2.5kg of material, if 0.1% of that material (not the mass, which is conserved) is converted into energy, gives the energy equivalent of 53.7 kilotons of TNT, which is more than the two nuclear bombs dropped onto Japan combined.

In conclusion you can shoot two nuclear bombs per minute with a recoil of a machine gun, provided you have magic that can convert 0.1% of matter into energy.

I'm killing you with my mind.

Just realized yeah Marisa is upside down with a rope around her broom firing at something that will never see the light of day looking completely epic, I never believed in overkill but for the first time I had my doubts

Who says you can't learn things here? XD

To get away from the science, Jesus, look at Utsuho's and Marisa's eyebrows.

I believe these three commenters, Dr Fine Rolo, Unicode, and Free Functor, are responsible for the complete genocide of all catgirls, indubitably so. D: Murderers! Murderers I say!

Dr_Fine_Rolo said:
I'm killing you with my mind.

Satori will you will you, with your mind.

Byakuren can do that to eh?

DO YOU GUYS HAVE ANY IDEA HOW MUCH CAT GIRLS YOU GUYS JUST KILLED~!!!??? TT____TT
Zetsubou-shta~! <---I think i spelled that wrong >_<
anyways this picture is EPIC XD

chaosfirestorm said:
Zetsubou-shita

There fixed. Close though

Oh god, what have I unleashed in this thread? I"m never using the word recoil in front of you guys again...

Should I point out that more than half of the effect of recoil that you feel from shooting most cartridges is from the effect of the jet of hot gasses escaping, the rocket-momentum problem of the bullet leaving the gun?

Yes, now with all due respect, shut-up Doctor

This pic makes me think there should be an "overkill" tag as it is both epic and overkill

I think Twilight Spark is relevant.

Conversations like this are the reason I frequent Danbooru.

As for my two cents:
Am I the only one who sees, not a beam of light, but a hail of stars?

This image brings up bad memories.

Bansho said:
As for my two cents:
Am I the only one who sees, not a beam of light, but a hail of stars?

No.

also, there is no kill like overkill.

That looks like almost enuff dakka.

There is never enough dakka!

Damnit, physics are rotting my life even here!

Looks like someone is having a bad day...

Hey, need another explanation for this picture? I got it:
This is Touhou, physics do not apply here

jagus12 said:
Hey, need another explanation for this picture? I got it:
This is Touhou, physics do not apply here

You're nearly right... the only point you missed here, is that this is magic. No matter wether it is touhou or not. Most magical attacks are basically flashy embodiements of the casters emotions and/or will. If your attack is filled with the intent to end a life, it will probably turn a yellow/black color, etcetc. The thing is, this isn't really shooting a laser, but making a beam of energy in fron of you. Damn, I lost my point there for a minute... anyway... The main point is: magic is forcing the world to bend to your will. meaning if you only want to shoot a laser, that can pierce an ant that stole your precious cookie, then it will fly towards the ant... depending on your ability to manipulate your already-shot spells, you can actually control it, but that's a never-mind for now... the main point is, unless you want to fly from the recoil of the spell, you won't.

In many fantasy and some SF, flashy abilities (sometimes including gunfire) ignore the law of momentum conservation, allowing the spellcaster to push away the target while not being pushed back him/herself. Yeah.

But I don't recall physics not working in Gensoukyou (I saw a translation 'Fantastopia' which I really liked, by the way) by itself, or any fantasy world for that matter. Spells and such special abilities may ignore normal physics but it's not really constructive to simply scoff it away saying that physics don't apply. Because unless the lore specifies it, one can't tell.

All you physics buffs going on about recoil are missing one thing. Look at their hands. None of them, with the possible exception of ⑥, are actually touching their attacks. No contact, no recoil. The source of the beam would have whatever recoil there would be (and presumably has a small amount of magically generated kinetic force pushing it forward to compensate.) but that wouldn't affect any of the shooters, unless you're proposing that danmaku somehow transfers that magically generated kinetic force into kinetic force on the caster in the opposite direction, to which I would say, you're now exiting the realm of physics and speculating about pure magic, as opposed to speculating on the physical results of magic, which is at least partially possible.

Dammit guys... All you'd have to do is allow yourselves to say "fucking magic." That's all you'd have to do, and everything would be explained.

MemphisMastermind said:
Dammit guys... All you'd have to do is allow yourselves to say "fucking magic." That's all you'd have to do, and everything would be explained.

Fucking magic, HOW DOES IT WORK?

Nilix said:
Fucking magic, HOW DOES IT WORK?

By magic! Magic works by magic! Crazy, I know, but trust me on this one!

>> No contact, no recoil.

The End. :)

anatole_serial said:
>> No contact, no recoil.

The End. :)

An unstoppable force emanating form an immovable object?

AbatedDust said:
An unstoppable force emanating form an immovable object?

Would generate no recoil unless physically connected to said object.

If they are touching, then I can't say, as both are impossible by the laws of physics.

Etaoin said:
Would generate no recoil unless physically connected to said object.

If they are touching, then I can't say, as both are impossible by the laws of physics.

One of them flies on a broom! Breaking the laws of physics isn't anything like as silly as bringing realistic physics into this in the first place!

Everyone said:
PHYSICS

I best the artist didn't think any of that and if he ever finds this page he'll have a great laugh :3

rocermocer852 said:
I believe these three commenters, Dr Fine Rolo, Unicode, and Free Functor, are responsible for the complete genocide of all catgirls, indubitably so. D: Murderers! Murderers I say!

chaosfirestorm said:
DO YOU GUYS HAVE ANY IDEA HOW MUCH CAT GIRLS YOU GUYS JUST KILLED~!!!??? TT____TT
Zetsubou-shita~!

MemphisMastermind said:
Dammit guys... All you'd have to do is allow yourselves to say "fucking magic." That's all you'd have to do, and everything would be explained.

I can't help but feel these kinds of comments are just excuses to be lazy and not think about it...

MemphisMastermind said:
One of them flies on a broom! Breaking the laws of physics isn't anything like as silly as bringing realistic physics into this in the first place!

That depends on your definition of magic. I tend to follow Arthur C. Clarke, to whom magic is just sufficiently advanced technology. From that perspective, nothing in this picture violates any law of physics.

Meanwhile, in what you quoted me as saying, an immovable object is in fact impossible by the laws of physics, as unless an object has infinite mass, any force, no matter how small, will cause an acceleration in the mass.

Meanwhile in this discussion, Reimu is busy using all her spellcards plus the one taped underneath her pantsu.

Everyone said:
Everything

Jesus fuck, guys. It's a picture. A PICTURE!

You are all arguing over the physics of a PICTURE!

Not only that, but a picture of a series that deals with MAGIC! Which is FICTIONAL! Which is not based on FACT!

this is the kind of thing I mean...

what good is commenting on a picture if you can't discuss it?

Robomorons said:
Jesus fuck, guys. It's a picture. A PICTURE!

You are all arguing over the physics of a PICTURE!

Not only that, but a picture of a series that deals with MAGIC! Which is FICTIONAL! Which is not based on FACT!

It's not like they're wrong in doing it, either so

Bansho said:
this is the kind of thing I mean...

what good is commenting on a picture if you can't discuss it?

I draw the line when the scroll bar is that of the size of an ant.

Do you feel it necessary to read all comments?

Bansho said:
Do you feel it necessary to read all comments?

Well, there are some diamonds in the ruff, if you know what I mean.

Everyone said:
stuff

Everyone saying that it's magic is right, it's MAGIC! You guys are using all the wrong units!

In accordance with the Law of Magical Inconsistencies, all the laws that govern the world of magic constantly changes, except this one. As such, I am using the new Luntoer's Law of Magical Movement to calculate whether or not there'd be rebound:
F = ma

Where F is force, M is mana, and A is Absolute Willpower. From a scale of 1 to 100, I'd say that Marisa's Mana would be: pretty darn high. Now that only leaves Willpower.
As we all know, to calculate Absolute Willpower, we use:
A = EIOU
Where E is effort, I is Intent, and I don't know what the hell OU is. Judging from Marisa's face, I'd say that whatever her Intent is, her Effort is pretty high. So that leaves Intent. This is where the problem lies. If she has high stationary Intent (Is), she won't have much rebound. But if she has even higher dramatic Intent (Id) she might rebound just for show. So I'd say that this picture doesn't have enough information to begin with.

luntoer made my head hurt when he said:
SCIENCE TYPE THINGS

Um.......k lets go with that.

Dr_Z said:
they're stopping a meteor.

Flandre already destroyed a meteor on her own which was heading towards the SDM though.

The blur effect doesn't necessarily have to be caused by the girls moving up; it could be the caused by energy from their beams blowing back on them. The possibility that really jumps out at me is heated air blowing back due to being rapidly super heated. In this hypothesis the girls have braced themselves with their flight powers, but loose clothing, hair, etc would be allowed to flap around, or fall off in the case of Marisa's hat. This would have to be an incredible amount of force to account for the bending of Marisa's broom, but notice the little stress shape next to the knot, which implies that Marisa is pulling back on the end, bending the broom due to her foot placement.

If we combine wind due to heated air expansion with light refraction due to shock wave caused by the air's sudden expansion, we can explain the visual effects in a somewhat believable way. 80kmph wind would be plenty to blow hair and hats around like that on a horizontal plane, let alone with them upside down in midair. Furthermore, Master Spark is loud as hell in game, so sonic energy also deserves consideration.

Lastly, am I the only one curious about the smoke trail coming out of Marisa's broom?

anatole_serial said:
>> No contact, no recoil.

The End. :)

I'm no Dr. but I think that's wrong. Marisa may not experience the recoil from a beam that begins ten centimeters in front of her hand, but that doesn't mean the opposing force just doesn't happen. If the glowing ball she's holding emits a beam in one direction, then an equal force is going to have to be emitted in the other direction so that the ball itself does not tunnel through Marisa's abdominal body cavity. Rockets are self-propelled, but you should never stand behind a rocket launcher being fired.

Do the forces at work here really have to be so huge though? It's not like we can see anything being pushed around by these beams; the girls actually seem to be moving in the same direction in spite of both the possible recoil and, you know, gravity. After all, a flamethrower produces a flashy reaction, but the only forces felt are a bit of push from the expanding air and the recoil of holding a hose.

DoctorVisigoth said:
I'm no Dr. but I think that's wrong. Marisa may not experience the recoil from a beam that begins ten centimeters in front of her hand, but that doesn't mean the opposing force just doesn't happen. If the glowing ball she's holding emits a beam in one direction, then an equal force is going to have to be emitted in the other direction so that the ball itself does not tunnel through Marisa's abdominal body cavity. Rockets are self-propelled, but you should never stand behind a rocket launcher being fired.

That's exactly what I was thinking. Just because Marisa isn't physically touching the beam, she is holding onto the Hakkero. One would think the force would transfer to her (if there is force in magic).

But my hypothesis: there's no recoil from magic, everything looks like it's being pushed back because of the overwhelming kinetic heat of the spells (like what Pumpkin Eater said).

Okay, who's the idiot who tried to pull off a panty raid again?

to quote my favotire Deadpan-snaker/Alien Girl pair:

-Laser. A high intensity pulse transparent ray.
-Did her really shoot beams from her eye?
-Those were not particle accelerators, but intensified rays.
-What difference does it make? I don't care whether it's lasers,
masers or atomic heat rays used to destroy Mothra's cocoon, it's
all the same. The problem was, why did she fire atomic heat
rays even when there're no monsters around?
-It's intensified rays, not atomic heat rays.

i can't think of a better way to describe how i felt after some posts above...

Kammak said:
To get away from the science, Jesus, look at Utsuho's and Marisa's eyebrows.

I'm thinking FLCL thar...

Robomorons said:
I draw the line when the scroll bar is that of the size of an ant.

So long as that scroll bar ant doesn't take my cookie...

Wait, Marisa? Flandre? Utsuho? All in one? Wait, Patchouli's there too.
These trio of mass destruction firing at the same target? Rin Satsuki or Kazami Yuuka or Yukari Yakumo?
This happened before in Imperfect Metamorphosis

Despite the lengthy physics-or-not-physics discussion it’s not speculation fuel because according to the artist’s comment on Pixiv there’s an invasion from the outside world and they’re intercepting it over the Forest of Magic.

kittey said:
..there’s an invasion from the outside world and they’re intercepting it over the Forest of Magic.

Knowing that... this picture is so much more epic.

DoctorVisigoth said:
I'm no Dr. but I think that's wrong. Marisa may not experience the recoil from a beam that begins ten centimeters in front of her hand, but that doesn't mean the opposing force just doesn't happen. If the glowing ball she's holding emits a beam in one direction, then an equal force is going to have to be emitted in the other direction so that the ball itself does not tunnel through Marisa's abdominal body cavity. Rockets are self-propelled, but you should never stand behind a rocket launcher being fired.

The beam source itself would recoil, yes, but that doesn't mean the recoil is necessarily transferred to the caster. Clearly some force is pushing the beam source forward, but it certainly is not the caster, at least in a non-magical way, as they are not touching. Perhaps the caster uses some variant of telekinesis to push the beam source, and perhaps telekinesis does transfer force to the caster, but again, this is speculation about magic, not physics.

All we can say without waving our hands about magic is that if there is any recoil felt by the caseter, it is not generated in the normal way described by physics, but by some consequence of the way magic works. Hence, my argument is that trying to calculate the physics involved, as was done by the comments above my first, is pointless without greater knowledge of the way magic works.

Nilix said:
Fucking magic, HOW DOES IT WORK?

SCIENCE!

Etaoin said:
asdfghjkl

it's been over 2 years and we are still debating this. i love danbooru

I love this whole long thread of comments. I just want to hug it.

Flandre: Is that the best you got? doesn't hurt.

Outside world invasion? I guess Colonel Longhena decided to trial Hibachi in Gensokyo.

Sorry for the slight necro, but in regards to what luntoer mentioned earlier:

luntoer said:
If she has high stationary Intent (Is), she won't have much rebound. But if she has even higher dramatic Intent (Id) she might rebound just for show.

I think this was drawn for a very high amount of quality "dramatic Intent (Id)". I mean, if there was recoil, why would Marisa's hat be floating above her head (falling to the ground?) Why would it JUST NOW start falling? Why would there be shock rings around the beams? Utsuoho looks like she's blasting a pretty huge blast of flame, Patchy has several stabilizing magic circles, and she's using some Philosopher's Stones for extra power. Shanghai is assisting Marisa with her own star-beam. Heck that's literally what Marisa is also blasting away with! And Flandre...well, hell she just pitched a freakin' beam with Levaetienn. With the way her arms are positioned, it looks like she's just taken a huge swing, and blasted out that...well...blast.

I bring your attention to Marisa's hat again. With this incredible amount of dramatic Intent, it is the pseudo-force wind that is actually forcing the hat to "blow" off her head. She probably has spells that keep her hat in place when she desires it. But with the amount of willpower and force she is pumping into her blast, she might also be expecting the recoil and blast wind, so she feels them. It's magic. Why pump so much into such a flashy blast when, magically speaking, the same "effect" could be done with just the incantation, intent, mana, and proper sigils, and suddenly the target is blasted where it stands? No beams, no recoil, just the target being annihilated/repelled/etc. That's what magic is capable of. But no, characters like Marisa LOVE big and flashy! She would put a lot of effort into making it flashy for the sake of it being big "F" Flashy.

Also, I LOVE this thread. Science, magic, discussions, funny quips, combinations of the above...It all makes Danbooru THAT much more fun! I hope you guys don't mind this necro for me to put in my own thoughts about this stuff...

no kill is better than over kill

Well... Assuming their shots are just that powerful... They could actually be bending the light around them and that's not motion blur. But if that's the case those are STILL some retardedly powerful shots that should have the collective recoil of trying to launch a god damn sun.

Pidgey fainted!

WORDS!...WORDS for everyone!

If they all joined to fight a common enemy, it must be a pretty damn powerful one, just imagine

Interesting how you've all ignored the "easy" interpretation:

Marisa is flying upward on her own, because everyone in Gensokyo learns flight spells, and *pushing* the broom. Why does she have a broom? Because witches ride brooms. Even if they don't actually need them. Marisa's all about that western witch imagery.

Let's note that not all physics are applied in Gensokyo, I mean for real. Someone once tested to see if Marisa's weapon features could work in real life and it was concluded false. It really is the purest form of Magic. Whatever this magic is in Touhou, it is most certainly a mystery.