Originally posted by adam warlockI've seen movies (not commercial, I mean police training movies) showing dudes wearing BPV's and not getting knocked over. Maybe if you were shot by a high power hunting rifle, not sure of that one.
Yeah but I was thinking about in ideal case. If a bullet proof vest has enough density to send a bullet flying backwards then it can surely absorb its momentum too.
What happens next depends on the human of course. Either he is strong enough and after the reflection stands on his feet or he falls down. I'm betting on the second case if we want to be realistic.
Originally posted by sonhouseYeah. Now that you menmtion it I remember one time a friend of mine saying that in the movies the effects of being are severely enhanced.
I've seen movies (not commercial, I mean police training movies) showing dudes wearing BPV's and not getting knocked over. Maybe if you were shot by a high power hunting rifle, not sure of that one.
I just got miseducated by hollywood. 😉
Originally posted by adam warlockWhich is not to say it doesn't hurt! It can still leave bruises and maybe even break a rib. It's amazing they stop bullets at all!
Yeah. Now that you menmtion it I remember one time a friend of mine saying that in the movies the effects of being are severely enhanced.
I just got miseducated by hollywood. 😉
Originally posted by adam warlockBased on your second sentence we're in agreement.
Yeah but I was thinking about in ideal case. If a bullet proof vest has enough density to send a bullet flying backwards then it can surely absorb its momentum too.
What happens next depends on the human of course. Either he is strong enough and after the reflection stands on his feet or he falls down. I'm betting on the second case if we want to be realistic.
Originally posted by twilight2007I believe we disregard the effects of recoil in the weapon firing the bullets and therefore on their flight path, yes. Is that what you mean?
We disregard "recoil", right? Sorry if this has been posted already.
I'm arguing that recoil of the bullets from the bullet reflector would have an effect.
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Originally posted by AThousandYoungEnglish is not my first language but I guessed what I was trying to say could be understood even if I didn't use the right words. In the context of the problem it is assumed that a vest can reflect bullets, but normal vests can't do that. They just absorb and disperss the oncoming projectiles kinetic enrgy. So I thought a bullet proof vest needed some additional quality to be able to reflect the bullets. I think that intuitively that additional quality can be related to its density. But what do you think a bullet proof vest has to have to be able to reflect bullets?
It made no sense. Density of vests does not cause bullets to repel backwards in the fashion described.
Edit: http://www.bodyarmornews.com/bullet-proof-vest.htm in this article they say that in order to a bullet proof vest be able to stop rifle fire it has to be made by semirigid or rigid materials like ceramics and metals. These materials have a greater density. So I think that in order for a bullet proof vest be able to reflect bullets its density has to be even greater. Of course we are talking about the situation idealised in the problem.
Originally posted by adam warlockSo I thought a bullet proof vest needed some additional quality to be able to reflect the bullets.
English is not my first language but I guessed what I was trying to say could be understood even if I didn't use the right words. In the context of the problem it is assumed that a vest can reflect bullets, but normal vests can't do that. They just absorb and disperss the oncoming projectiles kinetic enrgy. So I thought a bullet proof vest needed some a ...[text shortened]... has to be even greater. Of course we are talking about the situation idealised in the problem.
Yes. That quality is assumed to exist and is not explored in this problem. We are interested in bullet paths given that quality's existence, not how to make that quality reality.
It's a thought experiment, and cannot be duplicated in reality with current technology. The vest with tightly woven fibers isn't even the general idea here. We're talking about science fiction energy fields or some similar sort of nonsense.
Originally posted by AThousandYoungThe Sci-Fi energy field would be a good solution indeed. But my main point wasn't what the additional quality needed to be. My main point was that if the bullets were indeed reflected nothing spooky would happen to the bullets momentum. It'd be like when a tennis ball hits a wall, nothing more nothing less.
[b]So I thought a bullet proof vest needed some additional quality to be able to reflect the bullets.
Yes. That quality is assumed to exist and is not explored in this problem. We are interested in bullet paths given that quality's existence, not how to make that quality reality.
It's a thought experiment, and cannot be duplicated in reali ...[text shortened]... a here. We're talking about science fiction energy fields or some similar sort of nonsense.[/b]
Originally posted by adam warlockAnd my point was that bullets are made of lead, not hollow rubber, humans aren't made of brick and we aren't rooted deep in the ground. Thus there will be more interesting effects, like the man flying across the room as the bullet is reflected.
The Sci-Fi energy field would be a good solution indeed. But my main point wasn't what the additional quality needed to be. My main point was that if the bullets were indeed reflected nothing spooky would happen to the bullets momentum. It'd be like when a tennis ball hits a wall, nothing more nothing less.
Originally posted by AThousandYoungAnd my point was that bullets are made of lead, not hollow rubber, humans aren't made of brick and we aren't rooted deep in the ground.
And my point was that bullets are made of lead, not hollow rubber, humans aren't made of brick and we aren't rooted deep in the ground. Thus there will be more interesting effects, like the man flying across the room as the bullet is reflected.
Good thing you let me know that. I always thought it was the other way around. 😛 I was just using the physiscist approach to solve a problem: First you solve a simplified version to know the physics of the problem and what is supposed to happen. Than you attack the real problem and hopefuly its solution will come much more easily. Cause if you want to be realistic you have to take into account things things like bullets being deformed and so the collisions will be inelastic. Then since in the real world friction is always present we have to take that into account too. And then what about gravity? So I was just simplifying the question to focus in what's essential.
[b]Thus there will be more interesting effects, like the man flying across the room as the bullet is reflected.[/]
😲 What kind of ammo are you planning to use? I don't think that people will fly across the room just by being shot. It was already said on the thread that people can withstand the impact well enough. And a friend of mine that was an expert on fire arms said that in Hollywood the effects of being shot are greatly enhanced.
This strange reflector vest MUST break either the law of conservation of momentum or that of conservation of Energy (... unless of course the vest gives up some energy ... mmm could be interesting!)
Nobody has yet answered what happens to the momentum.
EITHER the guy moves bacwards when shot OR the vest is infinitely massive. Take your pick.
Originally posted by wolfgang59Bullet mass = 0.02 kg
This strange reflector vest MUST break either the law of conservation of momentum or that of conservation of Energy (... unless of course the vest gives up some energy ... mmm could be interesting!)
Nobody has yet answered what happens to the momentum.
EITHER the guy moves bacwards when shot OR the vest is infinitely massive. Take your pick.
Human mass =75 kg
Bullet velocity = 2000 mph
Above values are some numbers I picked from Google.
Initial momentum is carried solely by the bullet, 40 kgmph.
Final momentum of the bullet is minus 40 kgmph
The difference must be in the vest or in the human (or a mix of both).
If it´s all in the human...the human would move at less than 0,6 mph. Most humans can withstand that I guess.