Bullettproff?
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@Gurth said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
At least mine are bulletproof
nothing is bulletproof, only bullet resistant to varying degrees.
My safety glasses are for yardwork so as long as they keep the occasional flung stone or grass clipping out of my eyes it's job done. :-)
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@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
My safety glasses are for yardwork
Is that what kids call it these days?
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@Luhmann said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
My safety glasses are for yardwork
Is that what kids call it these days?
dunno.
if i was fucking i'd call it fucking. i'm gutting the flipping grass and don't want pieces of it in my eyes!~
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@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
gutting the flipping grass
I'm even more out of touch with the modern dirty slang then I thought
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@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
i'm gutting the flipping grass and don't want pieces of it in my eyes!~
What are you cutting the the grass with for there to be a chance it'll get in your eyes?!
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@loopback0 said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
i'm gutting the flipping grass and don't want pieces of it in my eyes!~
What are you cutting the the grass with for there to be a chance it'll get in your eyes?!
Landscaping
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@loopback0 said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
i'm gutting the flipping grass and don't want pieces of it in my eyes!~
What are you cutting the the grass with for there to be a chance it'll get in your eyes?!
well i use the weedwhacker every alternate week and that does tend to get bits everywhere, and every fifth week i trim the hedges... and of course quarterly there's the tree trimming...
and there's the gravel walkway that sometimes has stones migrate into the path of the weedwhacker or lawn mower.....
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@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
well i use the weedwhacker every alternate week and that does tend to get bits everywhere
The bits also tend to go outwards and away, not up and towards.
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@loopback0 said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
well i use the weedwhacker every alternate week and that does tend to get bits everywhere
The bits also tend to go outwards and away, not up and towards.
the vast majority do.
i'm protecting myself from that one that manages to fall way way way way off the bellcurve.
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@Tsaukpaetra said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
Have you seen the videos of visualizations of an average sneeze? That's what's happening with a typical mower, just constantly and lower.
Significantly lower. It's on the ground. I rarely even end up with grass more than like half way up my shin - it's nowhere near my eyes.
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@loopback0 said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
The bits also tend to go outwards and away, not up and towards.
Depends which way you're holding the strimmer
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@Jaloopa said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@loopback0 said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
The bits also tend to go outwards and away, not up and towards.
Depends which way you're holding the strimmer
If you're holding it wrong, then eye wear might be the least of your concerns.
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@loopback0 said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
holding it wrong
Maybe it's a way to trim a fox?
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@Gurth said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
oh. the same brand i use....
or not.... they look flipping identical to the 3M branded ones i use. you should be absolutely fine!
These?
At least mine are bulletproof, these only keep frogs out of your eyes …
I'm sorry, I have to ask: Is there much of a Wallace Frog problem where these are used?
Edit: 'd already by the post I was replying to. In my defense, I think I've caught @accalia's cold.
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@Gurth said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
nothing is bulletproof
That depends on the bullet (impact velocity, cross-section, material, etc.).
no, it depends on the situation, also i'd be surprised of those classes are rated as bullet resistant to anything more than a bb gun.
let's look up the quoted testing specs:
MIL-PRF-32432, CLAUSE 4.4.3.3.4
Spectacles shall be hit once with a 0.15 caliber, 5.85 (+/- 0.15) grain, T37 shaped projectile at 640 to 660 ft./sec at normal incidence (0 degree obliquity) to the primary lens at a location within each the left and right critical areas.
MIL-PRF-32432, CLAUSE 4.4.3.3.5
Class 2 Goggles shall be hit three (3) times with a 0.22 caliber, 17 (+/- 0.5) grain, T37 shaped projectile at 550-560 ft./sec, once on the left side and once on the right with both impacts at normal incidence (0 degree obliquity) to the primary lens at a location within the critical area. ...
hmm.... T37 shaped projectile is basically a chamfered cylider.
and let's see..... standard steel BB's are 0.17 caliber and nominally about 5-7 grains in weight (about half a gram) so are pretty close to the first test projectile. hmm... and a high end BB gun fires in the 550-650 ft/s range.
so yes. a BB gun falls smack dab in the range of ballistic resistance of the glasses... though i'd be hard pressed to call a BB a bullet.
let's look at an actual bullet.
the .22 caliber short cartridge is arguably the most common small caliber bullet, used for small handguns and holdout pistols.
the bullet is .22 caliber and 29 grain in weight. That's.... i'll call it close enough to twice the mass of the test projectile in the second test, so it will deliver twice the kinetic energy for the same speed.... so what's the muzzle velocity of the .22 short? 830ft/s.... oh deer.... that's significantly faster than the maximum of 560 ft/s of the test projectile, in fact it's 50% faster, which means that it will deliver 225% as much kinetic energy per mass, which the bullet already weighs twice as much as the test projectile.... meaning a total of.... 450% as much kinetic energy as the more energetic test projectile, which would say to me that even this small bullet is more than enough to defeat the ballistic resistance of the glasses.
so, yeah. i'm still calling B/S on that bullet proof claim. They're plenty fine for protecting you from ejected brass cartridges, and would probably protect your eyes from a BB gun, but anything bigger and they're just not up to the challenge. ... Maybe that's why the product page for the glasses talks about "ballistic impact" rather than "Bullet Proof" or even the actually correct term "Bullet Resistance"
But don't take my word for it. the quoted specifications are available for free online, as are the weights and typical muzzle velocities i used for my math, feel free to double check my math for yourself. Or get a watermelon, a spare set of glasses and take them to the range and put them to an empirical test. But if you do that, take video. Because watching a watermelon go pop never gets old. :-)
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@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
"Bullet Resistance"
That'd be measured in Ω (Ohms), yes?
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@dkf Really? You mean I've been mistaken to measure it by inches of penetration all these years?
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@RaceProUK said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
measure it by inches of penetration
The jokes write themselves…
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@dkf said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@RaceProUK said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
measure it by inches of penetration
The jokes write themselves…
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@loopback0 said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
well i use the weedwhacker every alternate week and that does tend to get bits everywhere
The bits also tend to go outwards and away, not up and towards.
Have you ever run a weedwhacker? You absolutely want to wear eye protection.
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@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
nothing is bulletproof
That depends on the bullet (impact velocity, cross-section, material, etc.).
no, it depends on the situation
That is what I said. But I have this feeling you’re reading too much into an offhand comment meant to support a joke about a typo on the page about the 3M safety glasses.
get a watermelon, a spare set of glasses and take them to the range and put them to an empirical test. But if you do that, take video. Because watching a watermelon go pop never gets old. :-)
I really wish I could just go and do that.
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@Gurth said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
That is what I said.
you said bullet proof exists. there is no such thing. there is bullet resistence.
@Gurth said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
But I have this feeling you’re reading too much into an offhand comment meant to support a joke about a typo on the page about the 3M safety glasses.
possibly. you gave me the opening to righteously geek out with SCIENCE! so of course i took it.
@Gurth said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
I really wish I could just go and do that.
you should. is fun.
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@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
you said bullet proof exists. there is no such thing. there is bullet resistence.
I said (in fewer words than this) that many things can be bulletproof, depending on the circumstances under which the bullet strikes them. You’re coming at this from the other direction, in trying to determine what is needed to stop a given bullet in order whether or not to claim it’s bulletproof.
you gave me the opening to righteously geek out with SCIENCE! so of course i took it.
That means I’ve done my good deed for this life, then.
I really wish I could just go and do that.
you should. is fun.
Yes, that’s the impression I get. Unfortunately, it’d be just about impossible to even try around here.
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@Gurth said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
that many things can be bulletproof, depending on the circumstances under which the bullet strikes them.
show me something that is bulletproof and i will show you a bullet that will defeat its protection. :-P
@Gurth said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
Unfortunately, it’d be just about impossible to even try around here.
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@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
show me something that is bulletproof and i will show you a bullet that will defeat its protection. :-P
Challenge accepted:
(Subatomic particles aren’t bullets, BTW :P )
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@Gurth I was gonna say a neutron star
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@Gurth said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
show me something that is bulletproof and i will show you a bullet that will defeat its protection. :-P
Challenge accepted:
(Subatomic particles aren’t bullets, BTW :P )
hmm.......
how bout that?
not a bullet? hmm.... okay then.....
the gravitational binding energy of earth is about: 2.4 x 1032 Joules.
Let's assume i build a gun that is gapable of firing a projectile from space at...... let's say...... .9c. That's pretty fast, but not impossibly fast. we've measured natural particles moving a bunch faster than that.
so.......
2.4E32 = 0.5 m (0.9c)2
that works out to a projectile mass of.....
about 3.6E16 kilograms to deliver an impact with enough energy to completely undo all of earth's gravitational binding energy and make us no longer a planet..... ouch.
let's see how big a projectile that would be....
hmm.... depleted uranium's pretty dense.... at 19.1 g/cm3 that's...... 19.1*100*100*100 g/m3 or 19.1 metric tons per cubic meter.
how much will i need?
hmm......1.8e3 cubic kilometers.
that's.... the size of a medium asteroid. there's several thousand in our asteroid belt that would be big enough.
so not impossible, but pretty improbable.
let's try something more reasonable.
the Chicxulub impactor released a total impact energy of approximately 4.20E23 Joules. that's nine orders of magnitude smaller than the energy needed to make Earth into Not-a-Planet, but still plenty enough to fuck up our day. Let's double that impact energy and see what we would have to get smacked with by our .9c gun to deliver that amount of energy..... 7.7E7 kilograms. That's a lot less than we needed to deal with before. that's..... 4000 cubic meters of depleted uranium or.... about 8000 cubic meters of carbonacious chondrite.... or a small asteroid, to the face, at .9c to completely fuck up all life on the plant..... that's a lot of energy, but it's doable......
we'd need help from Randal Munroe to accomplish it, but it is doable.
@RaceProUK said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@Gurth I was gonna say a neutron star
Another neutron star, doesn't matter how fast, as long as it impacts or gets close enough. let the novae do the rest of the work for you. ;-P
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@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@RaceProUK said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@Gurth I was gonna say a neutron star
Another neutron star, doesn't matter how fast, as long as it impacts or gets close enough. let the novae do the rest of the work for you. ;-P
But does it still count if the 'bullet' is annihilated in the process?
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@RaceProUK said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
But does it still count if the 'bullet' is annihilated in the process?
a bullet that exits your target is a waste of kinetic energy.
most bullets are designed to break up in their target to maximize energy delivered.
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@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
show me something that is bulletproof and i will show you a bullet that will defeat its protection. :P
A black hole.
I win.
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@anonymous234 said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
show me something that is bulletproof and i will show you a bullet that will defeat its protection. :P
A black hole.
I win.
Have you seen what happens when black holes collide?! it's not pretty for anyone involved!
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@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
Have you seen what happens when black holes collide?!
No, but I've heard it.
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@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
2.4E32 = 0.5 m (0.9c)2
No, no, no. You can't use KE = (1/2)mv^2 if the speed is close to the speed of light.
KE = mc^2((1/sqrt(1-(v/c)^2)) - 1)
This gets you a mass of 2e15 kg. 10% the mass you calculated. Quantities going vertical at the speed of light is how you end up with cosmic ray protons that hit like a baseball going 100mph.
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@MZH said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
This gets you a mass of 2e15 kg. 10% the mass you calculated.
oh! superlative!~
It's even more possible than i previously calculated!
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@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
we'd need help from Randal Munroe to accomplish it, but it is doable.
I disagree on semantic grounds: the word “bullet” implies a projectile fired from a small arm, not from a cannon or some giant mass driver. Your 3.6 • 10¹⁶ kg projectile doesn’t quite fit that criterium, I’m afraid.
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@Gurth said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
a small arm
Size is relative; the 'gun' would be small compared to, say, the Milky Way Galaxy.
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@MZH said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
KE = mc^2((1/sqrt(1-(v/c)^2)) - 1)
*twitch*
Ek = mc2((1-(v∕c)2)-0.5 - 1)
Sorry.
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@dkf said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@MZH said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
KE = mc^2((1/sqrt(1-(v/c)^2)) - 1)
*twitch*
Ek = mc2((1-(v∕c)2)-0.5 - 1)
Sorry.
Til @dkf doesn't like sqrt-ers...
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@dkf said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@MZH said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
KE = mc^2((1/sqrt(1-(v/c)^2)) - 1)
*twitch*
Ek = mc2((1-(v∕c)2)-0.5 - 1)
Sorry.
Meh. If you're going to format an equation then format it.
/ 1 \ | ------------------- - 1 | | __________ | 2 | / 2 | K = mc | _ / v | | | / 1 - ---- | | | / 2 | \ |/ c /
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@accalia said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
nothing is bulletproof
What about something like a lake? Shooting a bullet at a lake isn't going to do much.
Or how about air? You can't damage air by shooting a bullet at it.
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@MZH said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@dkf said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
@MZH said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
KE = mc^2((1/sqrt(1-(v/c)^2)) - 1)
*twitch*
Ek = mc2((1-(v∕c)2)-0.5 - 1)
Sorry.
Meh. If you're going to format an equation then format it.
/ 1 \ | ------------------- - 1 | | __________ | 2 | / 2 | K = mc | _ / v | | | / 1 - ---- | | | / 2 | \ |/ c /
@MZH You can still use unicode characters when doing that. With them, you can get something like this:
⎧ 1 ⎫ │————————————— │ │ ________ - 1│ K = mc²│ ╱ v² │ │ ┐ ╱ 1 - ——— │ ⎩ │╱ c² ⎭
The only major thing wrong with this is that the top of the root and the horizontal line above it are too far apart. Fixing that would require a proper math rendering engine as you can't use combining diacriticals to get the effect (or at least it doesn't work with this font rendering engine; YMMV…)
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@ben_lubar What about a shadow? Nobody ever damaged a shadow by shooting at it, though I guess your own shadow could use a shadow gun to shoot shadow bullets…
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@RaceProUK said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
Size is relative; the 'gun' would be small compared to, say, the Milky Way Galaxy.
Any sufficiently advanced technology is indistinguishable from a big gun.
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@dkf said in Accalia Reviews A <del>Headphone</del><ins>BonePhone</ins>:
Nobody ever damaged a shadow by shooting at it
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@accalia bulletproff is to measure the speed of bullets
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@RaceProUK said in Bullettproff?:
You mean I've been mistaken to measure it by inches of penetration all these years?
Surely it would be some function of $units of penetration (reciprocal? Might be a problem if anything's so bullet resistant that there's no measurable dent). Otherwise a material that a bullet won't penetrate has a very low bullet resistance.
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@accalia this calculation reminds me of an article on xkcd about a baseball at .9c doing lots of damage, because it starts a fusion reaction
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Status: And then this thread was jeffed. Noice.