Is it real? In the movies, when someone is shot by a gun, he will fly backwards.?

Question

How do we explain this in terms of physics?

Answer 1

Yes, the mythbusters did this, and discovered that basically no bullet they could fire could make a measurable impact on the dummy.

Consider recoil. The recoil on the gun will be at least as high as the momentum in the bullet (the bullet will lose some momentum to air friction, but the gun will get the full charge). That means that if the force of the bullet is enough to throw the person shot backwards 3 metres, then the gun will also throw the person firing it backwards at least 3 metres.

In fact, that makes the "Noisy Cricket" gun in MIB more accurate than most police drama movies. To be believable, either the bullets should not throw the people shot backwards, or the shooters should carom around the room like Will Smith. You can't throw the shootee without throwing the shooter.

Note: rocket launchers don't count, they expend the propellant through a hole in the back of the launcher, rather than transmitting it to the gun.

Answer 2

Someone did a similar experiment with a watermelon as the target, to simulate just the head being shot. They found that if the bullet made it all the way through the watermelon, the watermelon actually went towards the shot. I forgot the physics behind it, but they had some cool high speed photos of the experiment.

Answer 3

The poor unfortunate one that is getting shot suffers the fate of an inelastic collision. Lets assume the bullet fully stops when it hits the person. Then the total momentum of the bullet which is calculated by its mass time velocity would be transferred to the person getting shot. Momentum is always conserved so the total momentum would go into moving the person as follows:

Pb = m V = M v where m = mass of bullet; M = mass of person

v = velocity of person V = velocity of bullet.

So go figure out what a 30.06 bullet weighs and how fast it goes and see what happens when it strikes a 200lb person.

Answer 4

Mythbusters did do this one. They hung a pig carcass on a rope so that it could swing freely. They shot it will all kinds of guns, the pig barely moved. If the bullet would have enough momentum to knock somebody backwards, it would also knock the person of firing gun the gun backwards, simple conservation of momentum.

Answer 5

As others have said, it depends on the size of the bullet. It is a simple momentum transfer, the bullet transfers it's momentum to your body. A 70 gram bullet traveling at 1000 meters per second has the same momentum as a 70 kilogram person traveling at 1 meter per second, which is about 2.2 miles per hour which is walking speed. But a sudden push at walking speed is quite a punch, as you will realize if you walk right into a stationary person without stopping.

Answer 6

Maximus's answer is incorrect... ("speed of the bullet is too fast")
A Dub's answer is right. Momentum of the bullet is the key, and some bullets (e.g. .45 caliber military pistol) are very slow but very heavy. That particular weapon (the US Military "45") was designed to STOP an attacker -- knock him down. To do this, it uses a subsonic massive bullet, but it's not the most accurate pistol in the world at longer ranges.

Answer 7

Sounds like a good one for MythBusters.

If they tried it they would find that most hand held fire arms will not drive a person backwards like you see in the movies.

If you were to do the math, there just isn't enough force there.

Answer 8

In terms of physics, the guy to be shot is wearing a harness with a hook in the back. He's attached to a rope and when he's shot, his friends pull it to suddenly jerk him backwards. Then he lands on foam, laughs, gets drunk and gets in a fight at a bar with his friend who he later has to appologize to.

Answer 9

It depends on the caliber of the weapon but most of the time the movies make things a lil more dramatic. For example a 22 will barely make you move where a 38 will make you bend over fairly quickly and a 7.62 round will knock you off of your feet.

Answer 10

Um, im not for sure i think they have pulleys and belts strapped to them if they want that kind of affect in that paticular movie but a way to find out is if you have a dvd of the movie check out special features or go to www.google.com or ask.com or if the place where they shot the movie you can e-mail them or if they have a website just really obvious stuff like that bye!