5 ms·

For point of reference, shotgun slugs can be stopped by modern armor. It still cracks people's ribs through sheer impulse. A 50 BMG has 5 times the kinetic ener

For point of reference, shotgun slugs can be stopped by modern armor. It still cracks people's ribs through sheer impulse. A 50 BMG has 5 times the kinetic energy and 3 times the momentum of that. It's simply not enough to stop the bullet at these kinds of impulses, you need something to distribute the force over time as well as space. Cars use crumple zones for this purpose - the time it takes the front to deform is extra seconds over which the momentum change takes place, thereby decreasing the impulse. Even if we could develop some sort of powered armor that let you carry absurd amounts of armour I don't see how you could really solve this problem. The suit is still going to push back into the wearer's body with the same impulse, and crack bones when it does. Ultimately, the truth is human beings are just too squishy. #BringOnTheRobots

adrianN 9y ago
If we allow for powered armor I can imagine armor with appropriate crumple zones. But I guess with powered armor you also get to carry ridiculously huge guns...
CydeWeys 9y ago
Shotgun slugs are a lot less penetrative than .50 BMG though; they're proportionally heavier and travel slower. 12 gauge is .73 inches. You need significantly more thickness of armor just to stop the .50 BMG at all, by which point you've added so much more mass that you've gone much of the towards solving the higher impulse as well.
- j9461701 9y ago
  >Shotgun slugs are a lot less penetrative than .50 BMG though; they're proportionally heavier and travel slower. What does the word "proportionally" mean in this sentence? Because factually, the slug is about half the weight of the BMG round. >You need significantly more thickness of armor just to stop the .50 BMG at all, by which point you've added so much more mass that you've gone much of the towards solving the higher impulse as well. You're looking at elephant-stomping-on-you levels of force, and you're trying to say it'll be mitigated somewhat because you have 5 pounds of steel on your chest rather than 2 pounds. You will be a person salsa even if you strapped a kitchen stove to yourself. You don't seem to be understanding the magnitude of the forces involved.
  - trhway 9y ago
    >You're looking at elephant-stomping-on-you levels of force, and you're trying to say it'll be mitigated somewhat because you have 5 pounds of steel on your chest rather than 2 pounds. You will be a person salsa even if you strapped a kitchen stove to yourself. the momentum conservation means that the 5 pound of steel would be moving with the speed of 18m/s after full momentum transfer from the 45g bullet hitting it at 900m/s. 5lb at 18m/s - is like somebody would hit you with a frying pan. While painful and dangerous if say into the head, it is still much less so than getting the bullet directly. Even better result would be with a 25 lb steel plate - just 3.6m/s - like somebody would shove an office/kitchen table at you. Elephant leg say weights 250kg - that would mean that if you have an elephant leg as an armor in front of you, after being hit by a 0.50 bullet with full momentum transfer the leg will be moving at the speed of 0.18m/s - you can just slowly step away from it. >You don't seem to be understanding the magnitude of the forces involved. please enlighten us and correct my calculations above.
    - j9461701 9y ago
      I don't mean to be rude, but did you not understand what I wrote above? >the momentum conservation means that the 5 pound of steel would be moving with the speed of 18m/s after full momentum transfer from the 45g bullet hitting it at 900m/s. 5lb at 18m/s - is like somebody would hit you with a frying pan. The change in momentum over time is what matters, not the momentum itself. As I said above, think of a car. The momentum change on your body from going from 0 to 100 mph is a slight push on your chest....if you spread that momentum change over 60 seconds of steady acceleration. The exact same momentum change, if done over a few milliseconds from say smashing into a brick wall, is probably going to kill you. I mean this isn't rocket science, it's literally high school physics. >please enlighten us and correct my calculations above. I...did the math already? Did you not read it? The momentum change over the distance of 2 inches produces a force of about 360,000 Newton - a 6000 kg elephant just standing on you would produce "only" 60,000 newtons. He needs to be actively trying to stomp your daylights in to get the kind of forces we're talking about. 50 cal is the kind of round that you hit someone in the torso and their arms fly off. It was built to kill vehicles and planes, for people it is absurd overkill.

adrianN 9y ago

If we allow for powered armor I can imagine armor with appropriate crumple zones. But I guess with powered armor you also get to carry ridiculously huge guns...

CydeWeys 9y ago

Shotgun slugs are a lot less penetrative than .50 BMG though; they're proportionally heavier and travel slower. 12 gauge is .73 inches. You need significantly more thickness of armor just to stop the .50 BMG at all, by which point you've added so much more mass that you've gone much of the towards solving the higher impulse as well.

j9461701 9y ago
>Shotgun slugs are a lot less penetrative than .50 BMG though; they're proportionally heavier and travel slower. What does the word "proportionally" mean in this sentence? Because factually, the slug is about half the weight of the BMG round. >You need significantly more thickness of armor just to stop the .50 BMG at all, by which point you've added so much more mass that you've gone much of the towards solving the higher impulse as well. You're looking at elephant-stomping-on-you levels of force, and you're trying to say it'll be mitigated somewhat because you have 5 pounds of steel on your chest rather than 2 pounds. You will be a person salsa even if you strapped a kitchen stove to yourself. You don't seem to be understanding the magnitude of the forces involved.
- trhway 9y ago
  >You're looking at elephant-stomping-on-you levels of force, and you're trying to say it'll be mitigated somewhat because you have 5 pounds of steel on your chest rather than 2 pounds. You will be a person salsa even if you strapped a kitchen stove to yourself. the momentum conservation means that the 5 pound of steel would be moving with the speed of 18m/s after full momentum transfer from the 45g bullet hitting it at 900m/s. 5lb at 18m/s - is like somebody would hit you with a frying pan. While painful and dangerous if say into the head, it is still much less so than getting the bullet directly. Even better result would be with a 25 lb steel plate - just 3.6m/s - like somebody would shove an office/kitchen table at you. Elephant leg say weights 250kg - that would mean that if you have an elephant leg as an armor in front of you, after being hit by a 0.50 bullet with full momentum transfer the leg will be moving at the speed of 0.18m/s - you can just slowly step away from it. >You don't seem to be understanding the magnitude of the forces involved. please enlighten us and correct my calculations above.
  - j9461701 9y ago
    I don't mean to be rude, but did you not understand what I wrote above? >the momentum conservation means that the 5 pound of steel would be moving with the speed of 18m/s after full momentum transfer from the 45g bullet hitting it at 900m/s. 5lb at 18m/s - is like somebody would hit you with a frying pan. The change in momentum over time is what matters, not the momentum itself. As I said above, think of a car. The momentum change on your body from going from 0 to 100 mph is a slight push on your chest....if you spread that momentum change over 60 seconds of steady acceleration. The exact same momentum change, if done over a few milliseconds from say smashing into a brick wall, is probably going to kill you. I mean this isn't rocket science, it's literally high school physics. >please enlighten us and correct my calculations above. I...did the math already? Did you not read it? The momentum change over the distance of 2 inches produces a force of about 360,000 Newton - a 6000 kg elephant just standing on you would produce "only" 60,000 newtons. He needs to be actively trying to stomp your daylights in to get the kind of forces we're talking about. 50 cal is the kind of round that you hit someone in the torso and their arms fly off. It was built to kill vehicles and planes, for people it is absurd overkill.