If a very large man were running towards you and you shot him with a handgun (a Glock or something similar) what would happen to his body? Would his momentum keep him moving forward until he hit the floor, would he just collapse where he was or would he be thrown backwards? I’m sure there’s a way to work it out, but this is too much of a physics question for my numerically illiterate brain. Any help is appreciated.
You have seen too much Hollywood! If the energy from a bullet hitting a body would cause the person being hit to be thrown backwards, then the shooter should have been thrown backwards as well...simple physics. Even if you ignore that, if we presume that the bullet was a 9mm (one of the most common from a handgun) then it would have a mass of between 115 and 147 grains, which is between 0.26 and 0.336 ounces and would be travelling probably between 1,100 and 1,300 feet per second. Being 9mm that would mean - ignoring any flattening upon impact - that the diameter would be between 0.355 and 0.357 inches. So you are talking about something the size of about 4/10 of an inch in diameter weighing at most 1/3 of an ounce hitting the body real fast, hence penetration of the body. Yes it would hurt, yes it could very well kill you, but there is not nearly enough energy even at maximums to throw anyone backwards. Most common means of death occurring immediately would be damage to the central nervous system. Any other damage from a single round is not going to cause immediate death, although depending upon what was hit there may only be seconds or minutes before death. Lot's of stories of people being shot multiple times and surviving; not that I would want to try it. So if you hit the central nervous system (brain, spinal cord) then it is possible they would drop right there; if they were hit they may decide on their own to stop; either way whatever forward momentum they had would continue even for a short distance given the low mass of what is hitting them compared to their momentum/weight. Doesn't really matter if it were a large man or someone/something rather small. Hope this helps.
Considering a 9mm is pretty small, yes if hit in the head (provided it doesn't deflect off the skull being a lighter load) and he died, foward momentum would carry him forward since 180-200 pound man out weighs that of the bullet traveling at him. Hitting him in the abdomen would slow him down, since the liver and kidneys are not protected by the ribcage, along with the intestines. If you stepped up to a .45 cal. the bullet will be bigger heavier and moving a bit slower, and cause more damage by mass. Still won't effect momentum of the man in motion. In the unlikely event your MC happens to be carrying: It fires a .50 BMG, which would probably break their hand from the recoil, but would definitely would slow or kill the guy, depending on where he is hit. In the least it would take a good chunk out of him, because it is a massive slug moving pretty fast. Even then he would still fall forward upon impact. I hope this helps a smidgen, and I don't think your MC needs anything powerful enough to take down a T-Rex if it were to break into their home.
Thank you, this helps a lot. I’m terrible at physics (pretty sure I have dyscalculia [basically numerical dyslexia], anything beyond simple adding/subtracting and my brain shuts down completely) so working out anything to do with force/speed etc are well beyond me. Thanks for taking the time to answer.
No problem. If you are going to write much of anything related to firearms, might I suggest that you visit a range with a friend who is a shooter, or take a lesson, and try to shoot a firearm? It might change your perspective to get some real world experience. It will certainly help with being able to describe feel, look, smell and of recoil. Virtually everything shown in TV & Movies contains numerous inaccuracies, mistakes, etc. when it comes to firearms.
Mind that a good portion of recoil (shooter's side of physics) is absorbed through proper posture and an upwards movement of the pistol. This is mostly to the arguments above. A 9mm has stopping power but definitely not a send-flying power. A familiar shooter would likely not stop at one shot, but deliver 4-8 shots in succession.
This is really helpful, thank you. And I might use that last one for my sequel to the Jurassic Park franchise: Jurassic World 4, Will They Ever Learn?
Depends on a whole list of factors. Foremost, bear in mind that terminal ballistics (what happens when the bullet reaches its target and what it does immediately after) is a strain of weird science bordering on witchcraft. There are enough variables in the equation that one-in-a-million shots aren't as rare as might be imagined. As has been pointed out, energy is key. There are weapons and weapon systems that will physically throw a man off his feet. Most of these are not considered man-portable, and therefore unlikely to appear in your average defensive shooting. Physical and mental attributes play a major part. Will to live (or to press an attack) is a wild card. Modifiers to this include mentality, focus, training, and the effects of any narcotics present. I am assured by friends who've seen their share of fights resulting in gunshot wounds that berserker rage is very much a thing - but so too is the sudden loss of will to fight after the drawing of first blood. Generally speaking, most allow a couple of ways to stop an attacker: 1) Let the air/blood out. This means you cause enough damage to the respiratory system that oxygen doesn't get into the bloodstream or enough physical trauma that sufficient blood is removed from the body to starve the brain. This may take some time, and depending on how motivated (or doped) he is, he may still have time to do you significant bodily harm. 2) Break a leg or any component thereof. If an attacker can't stand, he can't run. This doesn't necessarily prove lethal, but it does give the intended target the chance to open the range and possibly avoid any physical confrontation. 3) Shut off the lights. On some styles of law-enforcement paper target you'll find a T-shaped target box overlaid on the face, representing the connection of the brain stem to the skull. A bullet placed inside this perimeter can be safely assumed to mean an end to the fight. Probably the hardest to pull off, this one is most useful if your bad guy is holding a hostage or wearing a dynamite vest. Anything outside those three may end the fight (and the perp)...then again, it may not. Humans can be a surprisingly resilient animal, and though Hollywood tends to underplay the effects of being shot, a good percentage of those who are will generally survive provided they receive adequate medical care in short order.
Its unlikely that even a very powerful round like a 50AE would send you flying, chances are it would blow through leaving an impressive exit wound but it wouldn't arrest the momentum of a man charging forward
