Wanted - Curving Bullets

Bullets, as well as facts, get curved in this week's Reel Physics.

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You should revisit this movie and check the scene where she gets in a moving car.

Yeah, it's pretty well known that this scene is pure hollywood BS, thanks to the Mythbusters. It is nice to see all the math involved though.

Slight mathematical error, when you give the time for the bullet on the tip, you said it was .03/1000 seconds or 3/10000 of a second. One of the two is wrong, it should be 3/100000 if the first one is right.

And thus the one gun movie that I could not see because the idea of a person being able to "curve" a bullet is the most BS thing that Hollywood wanted me, personally, to swallow. It was too much of a "Jumping the Shark" kind of movie to me. :P

How about that scene from RED, where Bruce Willis walks out of the police car spinning around? :p

Just for fun. :3

EDIT: Or just, this whole scene.

Man, this movie.

So how plausible was my alternative suggestion from last week, to make the bullet curve by:
a) Making it with an asymmetrical cross-section
b) Ensuring it is inserted into the barrel at a set orientation
c) Not rifling the barrel so the bullet emerges without any spin

I guess if we're being really fancy there's no reason the bullet couldn't be given wings and a tail!

I'm sure it's possible to make it work, but is it possible to make it effective and accurate?

fun episode.
if you think that math is hard, check the bicycle riding formula!

yeah.
really

therandombear:
How about that scene from RED, where Bruce Willis walks out of the police car spinning around? :p

Just for fun. :3

I have no idea how they would figure that, but I second the suggestion to try. Might be an interesting one to see if there is enough information to go on. They can figure out how heavy these cars should be, but without speeds it's be hard to really figure.

But, back to this weeks. I really enjoy seeing stuff even if I already know that it is impossible, because it's fun to see the math and see just how impossible it really is.

Flatfrog:
So how plausible was my alternative suggestion from last week, to make the bullet curve by:
a) Making it with an asymmetrical cross-section
b) Ensuring it is inserted into the barrel at a set orientation
c) Not rifling the barrel so the bullet emerges without any spin

I guess if we're being really fancy there's no reason the bullet couldn't be given wings and a tail!

I'm sure it's possible to make it work, but is it possible to make it effective and accurate?

IIRC the Mythbusters covered some of these, carving into the contours of the bullet and such. Best I remember all it ever accomplished was making the bullet tumble, just too much energy behind it. You would need an actual spin to have it curve.

Only saw that episode once, so I might be remembering wrong.

mew4ever23:
Yeah, it's pretty well known that this scene is pure hollywood BS, thanks to the Mythbusters. It is nice to see all the math involved though.

I think this episode was less about "is it possible," seeing as how they said several places have already shown that it isn't, and more "what would it take for it to be possible."

I'm no ballistics expert, but it seems that their calculations and ideas are flawed from the get go on this one.

My understanding of the whole rifling concept (and if I'm wrong, I'd welcome corrections) is that the barrel is barely wide enough for the bullet to travel through without jamming up, and the rifling then "cuts" into the bullet to spin it.

To me, this says that there's no way the barrel could impart an angle to the bullet the way they've demonstrated. It simply isn't wide enough to permit that.

As I said, I could be wrong.

Couple of comments (but first, let me get out my geek card from my wallet):
1) Due to conservation of momentum, suddenly altering the angle of the bullet to 45 degrees will cause the bullet to spin "end-on-end". Since this happens, you can't really use the Kutta-Joukowski theorem for a cylinder.
2) Although this deviates from the movie, a more effective way to curve a bullet would be to use an actual spherical bullet (e.g., a musket ball) [note, this would be an awesome movie]

For fun (please feel free to double check my equations):
A 1700's German wheellock musket can fire a .035kg, .009m radius musket ball at roughly 400m/sec. The scene in wanted showed a shot curving about 0.1 meters from the center of a person's head when fired from about 5 meters away. This implies a radius of curvature of about 125 meters. This in turn translates to a required centripetal force of 44.8 kg*m/s^2.
According to the Kutta-Joukowski theorem for a sphere (assuming an air density of 1.15 kg*m^-3), attaining this force would require a spin of 2540.6 rotations per second, or a rotational velocity of 143.6 m/s. To obtain this, the shooter must apply this velocity within 0.0000225 seconds. Assuming that the gun weighs 2.5 kg, this would require a force of approximately 16000000 kg*m/s^2 (this is about half the force generated by a Saturn V rocket).

Once again, please feel free to double check my work!

I'm going to stop watching this series, I have no clue what the hell is going on when the first formula pops up. Then it's followed by more formulas and I'm like WTF

KITTY!... Ahem, what I mean to say is that despite the awful violations of common sense and logic, understanding of physics, etc, you manage to make me want to see all the movies you feature.

iamjonah:
Couple of comments (but first, let me get out my geek card from my wallet):
1) Due to conservation of momentum, suddenly altering the angle of the bullet to 45 degrees will cause the bullet to spin "end-on-end". Since this happens, you can't really use the Kutta-Joukowski theorem for a cylinder.
2) Although this deviates from the movie, a more effective way to curve a bullet would be to use an actual spherical bullet (e.g., a musket ball) [note, this would be an awesome movie]

For fun (please feel free to double check my equations):
A 1700's German wheellock musket can fire a .035kg, .009m radius musket ball at roughly 400m/sec. The scene in wanted showed a shot curving about 0.1 meters from the center of a person's head when fired from about 5 meters away. This implies a radius of curvature of about 125 meters. This in turn translates to a required centripetal force of 44.8 kg*m/s^2.
According to the Kutta-Joukowski theorem for a sphere (assuming an air density of 1.15 kg*m^-3), attaining this force would require a spin of 2540.6 rotations per second, or a rotational velocity of 143.6 m/s. To obtain this, the shooter must apply this velocity within 0.0000225 seconds. Assuming that the gun weighs 2.5 kg, this would require a force of approximately 16000000 kg*m/s^2 (this is about half the force generated by a Saturn V rocket).

Once again, please feel free to double check my work!

Too bad it doesn't become possible (only less impossible). The movie would be at least 50% better if they used muzzleloaders. I do recall two or three such weapons in the movie, most notably the flintlock pistol Wesley's "dad" uses when jumping from building to building, and the huge musket that's used to assassinate him.

chetoos:
Slight mathematical error, when you give the time for the bullet on the tip, you said it was .03/1000 seconds or 3/10000 of a second. One of the two is wrong, it should be 3/100000 if the first one is right.

Yeah I saw that and thought WTF? 0.03/1000 = 3/10000??? LOL reel physics you suck etc.

tkioz:
The math... oh my... the math... I think it broke my brain.

Happens to me in every episode!!

You've been reel physicin a lot lately, I liked it more when they actually are possible and my reaction is completely WTF!! O.o
Like the flying tank scene, that was insane :P

I highly appreciate the inclusion of cat in this episode. =3

So only once you discard all the logicalities, bullshit happens? *cough* Sounds a lot *cough* like *cough* religi-*cough* *cough* *COUGH* Oh, this one's really getting to me. *cough*

"So you're saying there is a chance." - Dumb and Dumber

Lawyer105:
I'm no ballistics expert, but it seems that their calculations and ideas are flawed from the get go on this one.

My understanding of the whole rifling concept (and if I'm wrong, I'd welcome corrections) is that the barrel is barely wide enough for the bullet to travel through without jamming up, and the rifling then "cuts" into the bullet to spin it.

To me, this says that there's no way the barrel could impart an angle to the bullet the way they've demonstrated. It simply isn't wide enough to permit that.

As I said, I could be wrong.

They specify they were over simplifying and treating it as if the barrel were ONLY acting on the edge of the bullet, whereas in reality it doesn't work that way.

We all knew it was impossible, they were just calculating HOW impossible.

Nice episode usual, but let just take out the real facts and put in the reel facts (see what I did there:P) for a second.

If you look at the scenes where they curve bullets (notably the one with Angelina in) you will see that Angelina's hair sways in the passing of the bullet. I dont know about you but I have never seen hair sway that fast that a bullet barely pass it before it has swayed!

What im trying to say with this is that everything Angelina(her character of course) does must be super fast, even the stuff she cant control, or the bullet travels slower then a bullet in real life!

So what if you could find out at what speed the bullet was traveling at based on what we see. We all know things that move slower have a tigher curve.

OlasDAlmighty:
Okay, I wanna know, does anyone else just kinda zone out when they start getting into the complex math? I mean, I get the gist of what they're saying and all but when those equations pop up my brain just sorta runs and hides.

Yeah I know, my brain starts listening again when they conclude the equations and gives us the answer to them.

only the title made me think that you would either need new heads again for this episode or you would just stand there for 3 minuites and yell no the entire time.

i was pleasantly suprised. although i had hoped you would've rather taken the car chase scene..

I KNOW SOME OF THESE WORDS!

You know your movie is bad when the story is MORE realistic as a super-villain story with World wide mind control, Aliens, 5th dimensional imps, immortals and living evil shapeshifting poop!

therandombear:
How about that scene from RED, where Bruce Willis walks out of the police car spinning around? :p

Just for fun. :3

Now that's a good suggestion. Seconded.