Why do people go flying in films?

D

Dangus

New member
I was having a friendly physics debate with a guy about how people in movies go flying when hit by big guns.

When hit by a .357 or .44 you see people literally fly 10 feet on some cases, yet the person shooting feels almost no recoil...

I was arguing that fundemental physics would suggest that the person getting hit cannot recieve more energy than the person firing the gun. As in, the law of equal and opposite reaction. So, the real killing from a bullet is the focus of the energy, and the piercing, but that it can't throw someone if it can't throw the shooter.

He disagrees, saying that the person hit recieves more energy than the shooter and therefore can go flying. I don't think he's right.

Any thoughts?


------------------
The Alcove

I twist the facts until they tell the truth. -Some intellectual sadist

The Bill of Rights is a document of brilliance, a document of wisdom, and it is the ultimate law, spoken or not, for the very concept of a society that holds liberty above the desire for ever greater power. -Me

Compromising the right position only makes you more wrong.
 
You know more physics than he does.

The shootee can't receive more energy than the shooter. That's Conservation of Energy 101. In fact, due to air friction, the bullet has less energy at impact than when it left the muzzle (as predicted by the 2nd Law of Thermodynamics, which, paraphrasing, says that left to themselves, things turn to crap).

Having taken 15 quarter hours of engineering physics in college days, plus 9 qh of thermo, plus numerous other calculus- and mechanics-based engineering classes, it cracks me up when people without a clue as to the underlying physics try to pass themselves off as experts at Newtonian mechanics.
 
Warning! Math ahead!

Energy is one half mass times velocity squared.

Momentum is mass times velocity.

The momentum in the bullet has to equal the momentum left behind in the shooter. But the bullet weighs less than the gun, so it ends up going much faster than the gun recoils, and because energy is velocity squared, it gets most of the energy.

When it strikes, assuming it stops in the target, the target receives all it's energy and momentum. The target gets exactly as much momentum, (The stuff that sends you flying.) as you do firing. It just gets a lot more energy, the stuff that does damage.

Of course, this doesn't take into account muzzle brakes and muzzle blast. But generally speaking, you shoot somebody, they're not going to go flying any further than you, probably less. Unless you're firing rockets, that is...

Notice that the more the gun weighs compared to the bullet, the less energy remains in the gun. That's why holding the gun really tight helps reduce perceived recoil; You lend some of your weight to the gun, more of the energy leaves with the bullet, and less hangs around to hurt you.

------------------
Sic semper tyrannis!
 
What would make the person fly back would be MOMENTUM transfer. Momentum is the product of mass (m) and velocity (V). Linear momentum is conserved. If the bullet of mass (m) stays in a target of mass (M), the equation to describe the conservation of momentum in this situation is m*V1 = (m+M)*V2. Plug in the numbers for m, M, and V1, solve for V2, and you'll see the final velocity is tiny - we're talking INCHES per second for a magnum pistol shot hitting a human-sized target.

I've tested this with a full power .41 Magnum fired at an 18" piece of railroad tie (standing on its end)at point blank range. The tie rocked a bit, but wasn't knocked over. And it weighed far less than a man.

Movie stunts and special effects shouldn't be taken to mirror reality. If your friend still uses them as an example, ask him if there's any residue left when Capt. Picard uses a phaser set on Level 16. ;)
 
Okay, so I'm a physics major, but I'll ignore the theoretical aspects of this question and figure it out as an emperical matter:

Fortunately, few of us have experience shooting people, BUT many of us shoot critters. Deer weight about the same as people. How many times have you seen a 150lb deer fly 10 feet when hit by a .30-06? NEVER? that's odd.... the -06 is much more powerful (momentum and energy) than even a magnum handgun.

In my experience, a creature that gets hit usually just convulses, and falls to the ground.

Just hollywood being stupid again...

------------------
Abe Smith,
President of UW-Madison's
Student Alliance for Firearm Education and Responsibility
 
I agree; Hollywood trickery. Too many people take it as reality though. They believe in "high capacity" handguns that fire 95 rounds without reloading, nightvision scopes that see through concrete, shooting guns from bad guys hands, etc.
 
This has been fairly well hashed out by those above. I did want to mention, though, that the mass of the firearm does absorb (via inertia transfer) some of the energy of the acceleration of the projectile, keeping some of the E transfer down. Muzzle brakes and the like contribute further.

That said, I refused to watch a minute more of Last Man Standing, after Bruce Willis sends a man flying off his feet, crashing through a plate glass window and out into the street beyond with a quick burst from his twin 1911 Colts. It made me want to know where I could get anti-tank rounds for MY .45!
 
Yup, just Hollyweird stupidity. Flying bodies add to the drama and excitement. Good theater requires the suspension of belief, after all.

One of the minor epiphanies that occurs when I take a newbie shooting for the first time is the "power" in the handgun. Most comment that it feels completely different than they thought it would, and secondly, they quickly realize that there isn't a handgun round made that is capable of throwing a full grown man across the room and through a plate glass window. It's not that a handgun isn't awesome in it's own right, but they see that it's way different and that it just so badly misrepresented in movies and the media, it really opens their minds to the possibilty that there's a lot of things misrepresented about guns.

Sorry to ramble on, but all this "dramatization" crap sure has put the sheeple's knickers in a bunch - they're scared of what they don't know or understand, and because they're sheep, they don't have the gumption to investigate objectively. M2
 
Why do people go flying? Well, you see, they are hooked up to a harness that is then either hooked up to a spring-loaded contraption or sometimes a explosive-loaded contraption that is set up to give them a good yank at the appropriate time. The contraption is much more powerful than any guns used in the movie, but that is creative license.
 
A .45 ACP round will knock a man down like he was hit by a truck. The entry wound will be the size of the bullet and the exit wound will be the size of a dinner plate. If you hit a large bone it will lift him off of his feet and throw him backwards through a plate glass window.

The only problem- you can't hit anything with a handgun past 5 paces, although they are the most dangerous type of guns.

I know. I watch TV.
 
No O NO. A .45ACP goes in like a hypodermic needle and comes out like a buzzsaw!

------------------
You have to be there when it's all over. Otherwise you can't say "I told you so."

Better days to be,

Ed
 
Can one of you college boys please do the math and tell me what kind of handload WILL send a .357 LRN through a chevy big block?

My cousins brothers uncles sisters boyfriend said he's done it a couple times in his back yard.
 
lmao

------------------
The Alcove

I twist the facts until they tell the truth. -Some intellectual sadist

The Bill of Rights is a document of brilliance, a document of wisdom, and it is the ultimate law, spoken or not, for the very concept of a society that holds liberty above the desire for ever greater power. -Me

Compromising the right position only makes you more wrong.
 
It's the movies, folks. Graphics 'R Us!

Very few directors and producers in Hollywood, know anything about firearms (other than they hate them and want mine and your's confiscated), but they do know what they like to see on screen.

So.... BLAM! and somone goes flying back through a plate glass window.

Tinsle Town, a Place of Illusion.

J.B.
 
Gonzo,

Even .50 BMG ball ammo has trouble doing that correctly every time.....

------------------
The Alcove

I twist the facts until they tell the truth. -Some intellectual sadist

The Bill of Rights is a document of brilliance, a document of wisdom, and it is the ultimate law, spoken or not, for the very concept of a society that holds liberty above the desire for ever greater power. -Me

Compromising the right position only makes you more wrong.

[This message has been edited by Dangus (edited November 02, 2000).]
 
..except in Tremors 2. :D

------------------
WARNING: This post may be another "self-aggrandizing attempt to cause needless controversy, argument, distraction"
-*-
Keepin' the FUD Legacy Alive! Check us out @ FUD's Fan Club!
 
Pure Hollywood hype for dramatic effects.

Rich Davis of Second Chance Vests does one demonstration where he's wearing a vest designed to defeat rifle ammo. The shooter is point blank (less that three feet from him) and uses a FN-FAL (7.62 Nato) type weapon. Rich stands with his arms outstretched and one leg up. Blam! Rich is still standing. It's proof that it's all hype.

He reports of a Ohio State Trooper shot at close quarters with a 44 mag. She's only 5'4" and about 115 lbs wet. Despite being hit (thankfully in her vest), she stands and returns fire. I previously posted details of this under "Love Story" in the Gen. Disc. Forum.
 
10 or 20 years back, one of the gunrags, ( I don't remember which) tried shooting 7-8 pound utility grade rolled, boneless beef roasts off of 18" square platforms with all sorts of pistol rounds, up to and including the then king, 44mag. None succeeded in moving it more than a matter of inches. One load, the French THV 357 mag, (about 45 grains of hollow, pointy-conical brass at an UNBELIEVABLE velocity!) did, however, DESTROY its roast, resulting in over 50% mass loss ( the roast, not the slug ), but all the blasted apart beef went sideways, NOT to the rear! I'd LOVE to get hold of a little bit of that stuff!
crankshaft
 
You must log in or register to reply here.
Back
Top