# Can bullets knock people down? **URL:** \ **Category:** Factual Questions\ **Created:** [August 5, 2012, 11:19pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564 "2012-08-05T23:19:57Z")\ **Posts on this page:** 14\ **Page:** 3
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [August 11, 2012, 10:38pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564/41 "2012-08-11T22:38:21Z")
> [@gunnergoz](#): > > there is a famous clip from D-Day in Normandy where what appear to be UK troops are disembarking and running up the beach and one is hit and drops like a sack of flour. Drops right down, not forward, not back. . . . > Edit: just found it here: [http://www.history.com/videos/d-day-allied-invasion-at-normandy#d-day-allied-invasion-at-normandy](http://www.history.com/videos/d-day-allied-invasion-at-normandy#d-day-allied-invasion-at-normandy) at 1:23 in the video, he will be the running man on the left side of the frame. As an aside, and IIRC (I think I do), [those are not UK troops but, rather, Canadians; specifically from the North Shore Regiment of the 3rd Canadian Division landing at Juno Beach](http://www.youtube.com/watch?v=Ys4734ip0kE). See also [the 2nd photo](http://www.members.shaw.ca/junobeach/juno-4-0.htm) on this page. ---
**Author:** ![Freakenstein](https://avatars.discourse-cdn.com/v4/letter/f/b782af/32.png) [@Freakenstein](https://boards.straightdope.com/u/Freakenstein)\ **Post date:** [August 12, 2012, 3:30pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564/42 "2012-08-12T15:30:59Z")
> [@gunnergoz](#): > > one is hit and drops like a sack of flour. Drops right down, not forward, not back. He was running forward when he was hit and there was very little forward momentum, he just dropped more or less vertically…literally all the life and energy left that body in that instant. It could be he tripped, but his movement was not natural: it was more the fall of a dead weight. You’ve all seen when Mythbusters use ballistic gel and how it reacts in slow motion when a bullet hits it. Isn’t that same that happens with real flesh ( something like it happens with a slap to the face in slow motion ). So the bullet just doesn’t simply go through but it creates big shock waves ( that do the actual killing - like in shooting the fish in a barrel-episode ). ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [August 12, 2012, 4:01pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564/43 "2012-08-12T16:01:54Z")
> [@TriPolar](#): > > You’re describing the difference in the concepts of ‘knocked over’ here. Standing people are precariously balanced. It doesn’t take much to knock someone over if they can’t catch themself and rebalance. For a person standing on the balls of their feet, draw a line from one foot to the other and apply some force at right angles, and they can be pushed off balance easily. A pig carcass is like someone sitting on the ground, it takes a lot more force to move something like that. Did you catch that the pig carcasses in question are hanging from a leash with no contact with the ground? ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [August 12, 2012, 4:14pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564/44 "2012-08-12T16:14:12Z")
> [@Frylock](#): > > Did you catch that the pig carcasses in question are hanging from a leash with no contact with the ground? No. So then it would be impossible to knock to them over wouldn’t it? And it makes no difference. As long as someone can be knocked over by firing a gun, which does happen, then being hit with a bullet can knock someone over. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [August 12, 2012, 4:19pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564/45 "2012-08-12T16:19:37Z")
> [@TriPolar](#): > > No. So then it would be impossible to knock to them over wouldn’t it? And it makes no difference. As long as someone can be knocked over by firing a gun, which does happen, then being hit with a bullet can knock someone over. What? No, the point is that under those circumstances, the pig carcasses don’t even move. If the pig carcasses, (100 pounds, note,) suspended in air, don’t even move, it’s very difficult to see how a bullet could apply enough force to knock a person over. ---
**Author:** ![Normal\_Phase](https://avatars.discourse-cdn.com/v4/letter/n/5f9b8f/32.png) [@Normal\_Phase](https://boards.straightdope.com/u/Normal_Phase)\ **Post date:** [August 12, 2012, 4:26pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564/46 "2012-08-12T16:26:58Z")
> [@Flyer](#): > > However, a second cause of falling, and quite possibly the bigger cause, is simply the result of people thinking that they’re SUPPOSED TO FALL. After all, that’s what the movies show. In other words, people fall when shot because they’ve been conditioned to fall when shot. You know, speaking as someone who’s been in a sudden shocking traumatic situation (though not that one), I’m pretty sure you’re wrong here. Conscious thought is not high on the brain’s priority list when something like that happens; it takes a while. But I’d expect that, depending on the location of the bullet hit, there might be things like massive muscle contractions going on, or a shock to the nervous system, that is the normal cause of people falling, when they do. ---
**Author:** ![notsoheavyd3](https://avatars.discourse-cdn.com/v4/letter/n/85e7bf/32.png) [@notsoheavyd3](https://boards.straightdope.com/u/notsoheavyd3)\ **Post date:** [August 12, 2012, 4:30pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564/47 "2012-08-12T16:30:16Z")
Let’s set up some quick math. (Of course Chronos will correct me for using the simple version of momentum. Plus it depends if the bullet/baseball bounces off or not which would lead to a greater momentum change.) So lets look at some momentum since momentum is conserved. (Yes really. Really it is.) Anyway P = MV and with this we can compare momentum changes to find out how fast a different object travelling at a different velocity would have to go to get the same change. So MV = MV Lets say a baseball M(baseball)Velocity(baseball) = M(bullet) Velocity(bullet) which leads to Velocity (baseball) = M(Bullet) Velocity(bullet)/M(Baseball) So lets pick 45 ACP at 15 grams going 373 M/S vs a baseball at 149 g. From that we get a result that to get the same momentum change as the bullet the baseball would have to be thrown at 37.5 M/S or about 84mph. BTW using the above equation we can also figure out the momentum change of the victim. So if go with a 75kg male(165lbs) we can figure out that after being struck with that bullet he would move at about .0746 M/S which is 0.176MPH. ---
**Author:** ![notsoheavyd3](https://avatars.discourse-cdn.com/v4/letter/n/85e7bf/32.png) [@notsoheavyd3](https://boards.straightdope.com/u/notsoheavyd3)\ **Post date:** [August 12, 2012, 4:33pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564/48 "2012-08-12T16:33:39Z")
> [@Norse](#): > > (bolding mine) > > I don’t know if you’re referring to the former (muzzle blast momentum) or the latter (bullet momentum loss due to air resistance), but the momentum from the gunpowder gases is quite significant, at least for a rifle round. You can experience this quite easily by shooting a rifle with and without silencer. With a normal high-powered rifle round like a .223R or a .308W, a silencer will effectively cut the recoil by some 50% since the gases will exit the muzzle at relatively low velocities impacting only a negligible momentum to the gun. Actually I was referring to both. (Which means the shooter gets a larger momentum change than the target.) Anyway I didn’t know that which is kind of surprising since whenever I hear about the physics of a gun shot they don’t mention the momentum change due to the exhaust gases. (Which would actually make it less likely that a bullet would do anything, as you say there’s significantly more momentum change imparted on the shooter than the target.) ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [August 12, 2012, 4:39pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564/49 "2012-08-12T16:39:38Z")
> [@Frylock](#): > > What? No, the point is that under those circumstances, the pig carcasses don’t even move. If the pig carcasses, (100 pounds, note,) suspended in air, don’t even move, it’s very difficult to see how a bullet could apply enough force to knock a person over. Did you read what I’ve been posting at all. 1. It takes very little force to knock a person over. While standing, people are precariously balanced on two small points of contact with the ground. I can knock you over from any standing position with one finger unless you make an adjustment to your position after being pushed. And that adjustment is more difficult to do when you’ve been shot, especially from behind. I’ve knocked people over this way to demonstrate it, and it wasn’t difficult because even though they could adjust, they were so startled by how easy it was. Again, draw a line between the points of contact with the ground on someone’s feet, and apply force at a right angle midway between. That takes them off balance. A person standing is not a pig hung from a leash. I’m sure if you think about it you can see how unbelievably different a hanging pig is and how useless it is for making a determination of this question. Or do I need to explain that also? 2. Look at Chronos’ posts about momentum. Now certainly not all that force must be delivered to the person being shot, but depending on the gun, and the bullet, and where someone gets hits, like a major bone, then most of the force will be delivered. If it is enough force to knock over the shooter, it can knock over the shootee. And people get knocked over from firing guns if they fire from a bad stance. Specifically if they fire at a right angle from the midpoint of a line drawn between the two points of their contact with the ground. The answer to the question is “Yes, bullets can knock people down”. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [August 12, 2012, 5:22pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564/50 "2012-08-12T17:22:04Z")
It seems clear to me (but I admit I could be wrong) that the OP, and the thread discussion, are about the question whether bullets apply force sufficient to knock down even someone reasonably braced and expecting the blow. A force that can’t even move a freehanging one hundred pound weight–I doubt it can knock down a person in a ready stance. “Knock down,” btw, connotes to me something other than simply being pushed over. It connotes to me force sufficient to raise the feet off the ground if applied in the right direction. Maybe that’s ideolectical. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [August 12, 2012, 5:38pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564/51 "2012-08-12T17:38:10Z")
> [@Frylock](#): > > It seems clear to me (but I admit I could be wrong) that the OP, and the thread discussion, are about the question whether bullets apply force sufficient to knock down even someone reasonably braced and expecting the blow. A force that can’t even move a freehanging one hundred pound weight–I doubt it can knock down a person in a ready stance. > > “Knock down,” btw, connotes to me something other than simply being pushed over. It connotes to me force sufficient to raise the feet off the ground if applied in the right direction. Maybe that’s ideolectical. Ok, but that’s not clear or specified in the OP. And even if it were, denying the obvious effect I described is not an argument in favor of that. And offhand I can’t think of any other context where knocked over means anything else than the way I’m using it. You (and others perhaps) are asking if a bullet has the force to propel a person through the air. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [August 12, 2012, 6:08pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564/52 "2012-08-12T18:08:56Z")
> [@TriPolar](#): > > Ok, but that’s not clear or specified in the OP. And even if it were, denying the obvious effect I described is not an argument in favor of that. And offhand I can’t think of any other context where knocked over means anything else than the way I’m using it. You (and others perhaps) are asking if a bullet has the force to propel a person through the air. Yes, that is what I believed the question meant. From the fictional examples people cite, it does seem to be the topic on their mind. Ditto the counterevidence people are finding relevant–for example the pig carcasses. ---
**Author:** ![Rigamarole](https://avatars.discourse-cdn.com/v4/letter/r/77aa72/32.png) [@Rigamarole](https://boards.straightdope.com/u/Rigamarole)\ **Post date:** [August 12, 2012, 7:18pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564/53 "2012-08-12T19:18:34Z")
> [@bump](#): > > It’s more likely that the baseball would knock you down- it’s not spending its time penetrating your body like a bullet would be, so more of the energy is spent on impact to you, not in penetrating you. No wonder lesbians like softball so much. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 12, 2012, 7:20pm UTC](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564/54 "2012-08-12T19:20:51Z")
**notsoheavyd3** , I don’t see any problem with your calculations. If by “simple version of momentum” you mean non-relativistic, well, yeah, that’s perfectly appropriate here. [Previous page](https://boards.straightdope.com/t/can-bullets-knock-people-down/630564.md?page=2)