im not sure

...I was waiting for her to get shot in the head, and for that to be the point of contention.

No way that's real. Maybe it's a BB gun or something. Even if that was bullet-proof glass, the force behind the bullet from the gun would have to be enough to knock her back, or at least make that little glass pane go flying out of her hands or smack her in the face. The force behind the bullet would be much stronger than something to simply block casually like a rock being thrown.

The force from the bullet is the same as the recoil from the gun, no?

I doubt that pane of glass would stop rifle fire, especially repeated..

Dunno, looks real enough. They used to do some crazy stuff in the good old days

You fail at physics. The force of the impact is the same as the force of the recoil from the gun, which you can tell from the video, is not much.

It's hard to tell if it's real without knowing the composition of the glass. If it's a glass/plastic composite like most bullet-resistant glass, then it's probably real.

It also depends on the size of the round, which looks around 0.22 from what I can see.

Probably the Topperweins
holycraponastick

i just dont understand where all the energy goes
please* explain!

Newkid:

Newton's Laws tell us where the energy goes.

Expanding gas inside the barrel of the gun (between the bullet and the breach) force the bullet forward AND THE GUN backward with the exact same force. Hence, bullet flies out of barrel and the gun recoils.

After the bullet leaves the chamber, it is having no work done on it by our friend the gas, and is being acted on by gravity (it always was, but now it's more relevant because our dominant friend THE GAS has gone away) and air resistance.

The bullet falls (as fast as any falling object as it happens) and slows down in the air.

Then it SMACKS the glass, imparting its remaining kinetic energy (not sapped by air resistance) into the arms of our plain looking lady in the video.

I hope that was both informative and readable.

Oh, and in the end, the forces are transmitted via friction between the shoes of the people involved to the ground, and the earth wobbles a bit.

Probably. A larger caliber rifle would go right through.

So that's why I fell over!

I think she is pretty dumb to stand in front of a gun bullet proof glass or not

.

To add numbers into the discussion:

Let's say a guy's getting shot with a 9 mm handgun. The NATO standard 9x19 mm FMJ cartridge - the most likely round used if the target is, for example, a person - has a bullet weight of 7.5 g and the gun will have a muzzle velocity of around 350 m/s - just a little past the speed of sound.

Newton modeled a few relevant natural phenomena with some simple formulas: Most importantly for this discussion is p = mv, or the formula for momentum.

From p = mv, we know that the bullet has a momentum of about 2.6 kg*m*s[sup]-1[/sup]. Newton's laws say that momentum is conserved in a collision - whether it's elastic or inelastic. If all of the momentum is transferred to the person (it becomes embedded in them) the person gains 2.6 kg*m*s[sup]-1[/sup] of momentum.

Working backwards from the equation p = mv, if the person who got shot is 160 lbs they gained a velocity of 0.036 m/s from the bullet if they were standing on a frictionless surface - or 0.08 mph, if you prefer. If the person shooting them is using a Glock 17, they would need to empty two entire magazines into their target for him to reach a respectable walking speed.

Of course it's not that simple. We know that kinetic energy isn't conserved if the collision is inelastic - for example, if the bullet and/or person is deformed or damaged in the collision. We also know from W = Fd that the amount of kinetic energy transferred to a target is a function of the amount of interaction between the target and the bullet so if the bullet punches a hole through the target it probably won't experience much force.

And now you know why it's so stupid when they have a guy get thrown back 20 feet after being shot in a movie. It's actually a lot more realistic to have people deflecting the bullets with swords than it is to show them get ragdolled.

women were pretty submissive back in the day

Jon'C got it perfectly, but I feel I should expand on what he mentioned: the fact that even the meager amount of energy he describes gets spent largely on tearing through flesh and much less so on actually pushing the target back. FMJ 9mm rounds, from all of I've read, are likely to go straight through the target and still be carrying a decent amount of energy on the other side.

Also, if the rifle they're using is a 22lr (who knows) then the bullet will have about 1/3 the energy that he described. In that case, An automobile windshield would stop it.

You forgot to factor in F=mv.

yeah, F=ma doesn't work because if something's not accelerating then that means the impact has no force! hurr hurr

Horray for fyzzix!

he probably threatened to shoot her without protective glass if she didnt lol