4 ms·

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 spe

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.

trhway 9y ago
>The momentum change over the distance of 2 inches produces a force of about 360,000 Newton you're right that the force will be huge, and you're dead wrong about the force effect. lets say we stop the bullet over the distance of 1cm instead of 2 inches - the stopping force to act upon bullet would be even bigger - 1.8M Newtons (30 elephants!). The same value force will be acting upon our 5lb armor plate. This force will be acting until the bullet stops, ie. for about 0.02 milliseconds. During that time the force would accelerate the armor plate to the speed of 16m/s and the armor plate would travel less than 1mm - only starting to compress the padding under the armor plate. So, 0.02 milliseconds after the bullet impact we have a stopped bullet and the armor plate moving with the speed of 16m/s through the first millimeter of the padding - the situation is no different than being hit by a frying pan.
- j9461701 9y ago
  >lets say we stop the bullet over the distance of 1cm instead of 2 inches - the stopping force to act upon bullet would be even bigger - 1.8M Newtons (30 elephants!). The same value force will be acting upon our 5lb armor plate. This force will be acting until the bullet stops, ie. for about 0.02 milliseconds. During that time the force would accelerate the armor plate to the speed of 16m/s and the armor plate would travel less than 1mm - only starting to compress the padding under the armor plate. So, 0.02 milliseconds after the bullet impact we have a stopped bullet and the armor plate moving with the speed of 16m/s through the first millimeter of the padding - the situation is no different than being hit by a frying pan. That's not how impulse propagates. The force carries through the plate, into the person, and does its damage as a compressive wave. Think about seatbelts in a car during a high speed crash - they don't often penetrate the torso of people, but they can and do pop organs through compressive effects if they're worn too high. Yet calculate the momentum of the seat belt at 100 mph and you'll find it's tiny, like a light slap. But let's assume your analysis is true. Why then does a shotgun slug, with considerably less momentum than the .50 cal and even a frying pan, crack ribs through armor? Why can I put a piece of AR500 steel in front of a watermellow, hit the steel with a .308, and have the watermellon explode despite nothing getting through? But I'm done. I've explained this same concept 5 different times, and I'm still having to cover basic physics with people too proud to admit their layman's interpretation is wrong. If you think you could survive a .50 with armor, you're welcome to go buy a 1 inch plate from shootsteel.com and an M82 and test if out yourself. Remove one more prideful fool from the gene pool.
  - trhway 9y ago
    >That's not how impulse propagates. The force carries through the plate, into the person, and does its damage as a compressive wave. That would be true if the plate was pressed hard against the body. A force requires a carrier - a field or a matter. This is why there is padding behind armor. The padding air-gaps the body from the plate. Nothing crosses the air gap during the 0.02ms that the huge force you're talking about is acting between the plate and the bullet. The body isn't aware that something that violent is happening just a few millimeters away. At t=0.02ms the interaction between the bullet and the plate has finished and the plate is flying toward the body with the speed ~16m/s. At that t=0.02ms the plate has so far traveled only for less than 1mm and it will take it ~0.5 milisecond to cross the air gap and to slam into the body at about the same speed of 16m/s. Such slamming is like being hit by a frying pan. Can be pretty damaging if hits a joint or the head. May break a rib. Yet nothing close to being subjected to the force of being stepped on by an elephant or 30 of them. >Why then does a shotgun slug, with considerably less momentum than the .50 cal and even a frying pan, crack ribs through armor? The slug momentum (0.03kg at 540m/s) is 2.5 times less than that of .50 cal (0.045kg at 900m/s), so nothing surprising here, especially if it is through a flexible (i.e. different mode of action) kevlar armor. The steel plate armor we're discussing is much heavier. >Why can I put a piece of AR500 steel in front of a watermellow, hit the steel with a .308, and have the watermellon explode despite nothing getting through? Even if the watermelon is air-gapped from the steel, the watermelon still can't sustain being hit with a frying pan ( even with less than a full swing of it). If the steel isn't air-gapped from the watermellon - in this case the watermelon do get the force applied if the steel isn't fixed, or a compression wave by the steel plate vibration if the steel is fixed in place.

trhway 9y ago

>The momentum change over the distance of 2 inches produces a force of about 360,000 Newton you're right that the force will be huge, and you're dead wrong about the force effect. lets say we stop the bullet over the distance of 1cm instead of 2 inches - the stopping force to act upon bullet would be even bigger - 1.8M Newtons (30 elephants!). The same value force will be acting upon our 5lb armor plate. This force will be acting until the bullet stops, ie. for about 0.02 milliseconds. During that time the force would accelerate the armor plate to the speed of 16m/s and the armor plate would travel less than 1mm - only starting to compress the padding under the armor plate. So, 0.02 milliseconds after the bullet impact we have a stopped bullet and the armor plate moving with the speed of 16m/s through the first millimeter of the padding - the situation is no different than being hit by a frying pan.

j9461701 9y ago
>lets say we stop the bullet over the distance of 1cm instead of 2 inches - the stopping force to act upon bullet would be even bigger - 1.8M Newtons (30 elephants!). The same value force will be acting upon our 5lb armor plate. This force will be acting until the bullet stops, ie. for about 0.02 milliseconds. During that time the force would accelerate the armor plate to the speed of 16m/s and the armor plate would travel less than 1mm - only starting to compress the padding under the armor plate. So, 0.02 milliseconds after the bullet impact we have a stopped bullet and the armor plate moving with the speed of 16m/s through the first millimeter of the padding - the situation is no different than being hit by a frying pan. That's not how impulse propagates. The force carries through the plate, into the person, and does its damage as a compressive wave. Think about seatbelts in a car during a high speed crash - they don't often penetrate the torso of people, but they can and do pop organs through compressive effects if they're worn too high. Yet calculate the momentum of the seat belt at 100 mph and you'll find it's tiny, like a light slap. But let's assume your analysis is true. Why then does a shotgun slug, with considerably less momentum than the .50 cal and even a frying pan, crack ribs through armor? Why can I put a piece of AR500 steel in front of a watermellow, hit the steel with a .308, and have the watermellon explode despite nothing getting through? But I'm done. I've explained this same concept 5 different times, and I'm still having to cover basic physics with people too proud to admit their layman's interpretation is wrong. If you think you could survive a .50 with armor, you're welcome to go buy a 1 inch plate from shootsteel.com and an M82 and test if out yourself. Remove one more prideful fool from the gene pool.
- trhway 9y ago
  >That's not how impulse propagates. The force carries through the plate, into the person, and does its damage as a compressive wave. That would be true if the plate was pressed hard against the body. A force requires a carrier - a field or a matter. This is why there is padding behind armor. The padding air-gaps the body from the plate. Nothing crosses the air gap during the 0.02ms that the huge force you're talking about is acting between the plate and the bullet. The body isn't aware that something that violent is happening just a few millimeters away. At t=0.02ms the interaction between the bullet and the plate has finished and the plate is flying toward the body with the speed ~16m/s. At that t=0.02ms the plate has so far traveled only for less than 1mm and it will take it ~0.5 milisecond to cross the air gap and to slam into the body at about the same speed of 16m/s. Such slamming is like being hit by a frying pan. Can be pretty damaging if hits a joint or the head. May break a rib. Yet nothing close to being subjected to the force of being stepped on by an elephant or 30 of them. >Why then does a shotgun slug, with considerably less momentum than the .50 cal and even a frying pan, crack ribs through armor? The slug momentum (0.03kg at 540m/s) is 2.5 times less than that of .50 cal (0.045kg at 900m/s), so nothing surprising here, especially if it is through a flexible (i.e. different mode of action) kevlar armor. The steel plate armor we're discussing is much heavier. >Why can I put a piece of AR500 steel in front of a watermellow, hit the steel with a .308, and have the watermellon explode despite nothing getting through? Even if the watermelon is air-gapped from the steel, the watermelon still can't sustain being hit with a frying pan ( even with less than a full swing of it). If the steel isn't air-gapped from the watermellon - in this case the watermelon do get the force applied if the steel isn't fixed, or a compression wave by the steel plate vibration if the steel is fixed in place.