Oedipus Wreckx-n-Effect

I've been meditating a lot lately on humans that I hate.  I would say "people I hate," but once I take to hating a someone enough I de-classify them as a person.
 
I've been focusing on hate more because I've realized that there is no point in marinating in negative emotions.  What I had mistaken for righteous indignation was really jealousy.  I'm not angry at the fraudulent because I hate fraud; I'm angry because they're talentless hacks and I could do a far better job.  But I'm lazy, so you, my talented reader, you must do a better job, and become a more ravenous, vicious, and unstoppable leech than ever these mediocre reprobates could dream.
 
I got the idea when I was reading the latest drivel from our favorite poly sci majors, and I realized that the authors are fundamentally parasitic con artists, and, more to the point, half-assed ones.
 
The article is only worth reading if you want to heckle it.  It has no factual content.  The funniest part is probably where they're talking up the threat of firearms made on 3D printers, and then bring up the Ghost Gunner, which isn't a 3D printer.  It's a fucking mill.  You know, an example of that old-fashioned subtractive manufacture that's supposed to be obsolete now.  This is as intellectually honest as hyping the threat of being stung to death by zebras in the streets, and pointing out that tapirs will bite your fucking arm off as evidence of the severity of the threat.  I am, of course, heartened to see that these worms have doubled down on their claim that 3D printing is somehow applicable to clandestine manufacture of nuclear weapons, and are, as before, aggressively misunderstanding fundamental facts about isotope enrichment.  If there's anything that these scum are good at, it's ignoring basic fucking nuclear physics.
 
But other than that, it's not a particularly slick attempt to sew panic and profit thereby.  The best possible result from this sort of scaremongering is that some useless government regulatory agency will be set up to strangle 3D printing with useless regulations.  This useless agency will have some number of jobs that will be filled with poly sci majors and other unemployable refuse.  Anyone employed in this hypothetical useless agency would work nine to five in a cubicle, watching whatever their favorite deviant sort of porn is, calling in sick about a third of the time, and occasionally writing internal correspondence that will be beautifully devoid of meaning.  Is this sort of soul-raping mediocrity anyone's idea of a big steal?  Because if getting a fake job at a fake agency to police a fake threat is your notion of making it, please enclose yourself in a running incinerator.  You have some sort of pathogen that causes you to aspire to being a moderate nuisance, and that sort of plague needs to stop now.
 
The problem with these people is that their lies are small.  As we all know, big lies are better than little ones.  Don't stretch the truth; snap it right the fuck off.  The only thing standing between you and gigantic yachts made of cocaine is a sentimental attachment to the truth.  The lord of this world will only reward you fully if you embrace him fully.  Highly successful liars don't embroider the truth, they dispense with it entirely.  Consummate your marriage to darkness and falsity, and receive glorious rewards.  Don't say that the Eisenhower administration should have been more aggressive in defense spending and research.  Say that the Soviets have more bombers and more missiles.  You'll get to be president of Camelot, fuck Marilyn Monroe and will be spared the indignity of old age.  Don't say that 3D printing could change the way nuclear weapons are made in the future.  Claim that the Iranians and North Koreans, and hell, that the South Africans all made their nuclear weapons by using 3D printers.  When asked for evidence of your nonsense, point to the South African invasion of Sudan.  Say so with absolute arrogance and an unshakable air of moral superiority.  If you are loud and persistent enough, and lie outrageously enough, Satan will come through.
 
Don't shill for big coal companies by claiming that coal gasification technology will improve atmospheric conditions.  That's only stretching the truth.  You've got to go all the way, and just burn regular coal that you painted with Elmer's glue.  Your enemies will end up under review, and you'll get millions in tax credits.  Satan delivers.  Praise Satan.  But you have to be willing to go all the way with Satan.  Satan despises spineless, cowering wretches who sin a little to get ahead but still consider themselves fundamentally decent people.  Satan came through for the solar roadways bastards.  Satan came through for Leroy Jenkins.  Trust in Satan, and you will excel.  Don't you trust Satan?  Do you think that Satan is ignorant of your duplicity?  You cannot serve two masters.  Drink deep or taste not.

Stumbled on this gem of cdrsalamander being wrong, wrong, wrong about M855A1: http://cdrsalamander.blogspot.com/2013/07/so-anyone-consult-infantryman-on-this.html?m=1

Fun fact, my professior for heat and mass transfer used the second edition I believe. They used to like calling Incopera things like "incompetent".

Fast forward to him sharing an office at Sandia national labs with an individual who tragically lost the ability to feel or comprehend humor in any way.

My prof says, after seeing the same heat and mass text on his co-workers shelf on the first day of work, "oh, you have incompetent's book too huh?"

Mr no fun looks up from his calculus and says, in a monotone voice, "Incopera was my PI, and a great man."

That made for an awkward 3 years.

It is impossible to quarterback a police shooting without all of the data.  I know - I have done forensic analysis on 31 use of incidents in the past two decades and am a graduate of the SC police academy and 5 years of street work (part-time, but I was a full deputy).
 
On the one hand I agree with people who say police should be held to higher standards.  On the other hand - they usually are.  On the other other hand - some of the most egregious cases of police violence went unpunished.  Look up the real incident that lead to the creation of the TV show the Shield and the movie Traffic and tell me that police violence is not sometimes swept under the rug.
 
Police violence in the US won't be solved anytime soon because it is a double edged problem that requires two fixes.  The questions go hand in hand, but you cannot voice them in the same sentence to the same group without being called a name and shutting the conversation down.  The two questions are pretty easy to state.  #1 There are very very few cases of police shooting people who were not committing a criminal act followed by an aggressive posturing.  How do we teach people not to commit crimes and then charge police?  The second issue is similar.  Ambush of police is up across the board and across the United States.  If you are a cop and you are going to get killed in a crime, it will be when you are ambushed.  The current shoot / no shoot criteria is based on being right about the actions of a person you are facing 100% of the time or being quite possibly dead, so US police moved the shoot / no shoot line over - but then more people get killed.  How do we reduce ambushes allowing police to reset their shoot / no shoot point.
 
And a technological question.  Where is the ranged non-lethal weapon that will allow me to successfully deal with a 260 pound irate charging male before he enters by shoot envelope.  I was in a fight with such a man for nearly five minutes as he tried to get my gun, and you never know fear until you realize that your next mistake is your last and your wife and cats will never see you again.

Ugh. Reality needs to stop rewarding me for being a heartless evil right-winger.

Saint Cooper is alive and well.
 
Don't mind Deer Hunter's comments. He's a fud and smells his own farts. 
 
http://wethearmed.com/rifles/which-scout-rifle-anybody-own-one-and-has-any-input/

Interesting view on DIvision.

For fucks sake, if you think half of your population is retarded, maybe you're doing something wrong.
 
Here's a hint: Maybe send that 350 million pound a week to the education system or something.

Question time: are tortilla chips a viable snack on their own, or do they exist primarily as a salsa delivery vehicle? I say the latter (provided you have good salsa).

I made a shredded cassava dish for a party this weekend.  It was a hit, but I think they liked all the booze I brought even more.
 
Cassava is a root vegetable from Central/South America, but it apparently grows like gangbusters in Central Africa, so it's quickly become a staple there.  Recent archeological discoveries have shown that the ancient Maya ate quite a bit of cassava; earlier investigators had focused on the role of corn as a dietary staple.  However, the ancient Maya cities were pretty damn populous, and you can feed a lot more people with acres of cassava than you can feed with acres of corn.
 
In fact, the entire reason I had decided to make a cassava dish was that the man hosting the party had done a study on wear patterns of obsidian flakes in a cassava shredder of ancient design.  Back in the day when he did this you couldn't easily obtain cassava in the United States, so he'd had to make-do with potatoes.
 
I say "make-do," but while potatoes have only the slightest whiff of native flavor, cassava tastes like even less when cooked.  The varieties in the US (often sold as "yuca root" or "yucca") have a small amount of cyanide-producing chemicals that give them a delicious, roasty almost almond-esque aroma while they are cooking.  Not coincidentally, almonds have cyanogens in them too.  But once the cassava has been sitting in the pan for a bit, it is rendered an almost perfectly tasteless gooey starch.  You know tapioca pudding?  You know those little gelatinous blobs in it?  Those are made of cassava.  They taste exactly like fried cassava.  I.E. nothing.
 
Mislead by the delicious smells the root had emitted when cooking, I decided that this would be a dessert dish.  This turned out to be a good and simple choice.  I simply flavored to taste with coconut milk, sugar, cinnamon and coriander.  It came out roughly the consistency and flavor of walnut pie filling.  Except without the walnuts.  It was actually quite good with whipped cream or ice cream on top.

Wherein I tackle the idea of hydrogen fuel cell technology in private vehicles.
 
Buckle up.
 
For the past few years, Hydrogen Fuelcell technology has been making the news in regards to personal transportation. Regardless of how long fuel cell technology has been used in the space industry, the media treated it like a futuristic Godsend for personal vehicles. I recall there being plans drawn up for refueling stations in California, even. But the Bear State is fond of making whatever promise they can to skim as much money from its people.
 
See the High Speed rail fiasco.
 
http://www.bloomberg.com/view/articles/2016-06-28/california-hits-the-brakes-on-high-speed-rail-fiasco
 
When I first heard of hydrogen fuel cells being used in vehicles, I was too young and immature to have much of an opinion. Back then, I was still cruising around downtown and hanging out with Sturgeon to care about motor vehicle trends. Those nights were spent talking trash about HK products, doing blow through rolled up Benjamins, and dozens of questionably legal Polynesian women.
 
I'll be approaching this issue regards to efficiency, safety, production, and storage of many elements. We'll first discuss what hydrogen is.
 

https://en.wikipedia.org/wiki/Hydrogen
 
 
The Wiki gives a ton of great information. Most of you will know the basics. It's a gas at STP, contains a single valence electron in it's 1s shell (“shell” or cloud of probability derived by shrodinger's blah blah blah Physical Chemistry nonsense, don't make me do that derivation again). It was first artificially made by a guy named Cavendish, and is found naturally as a diatomic molecule.
 
This diatomic molecule also really likes to explode if it gets near an energy source. H2 combustion is well documented, and releases 286 kJ/Mol.
 
In fact, it can undergo combustion at as low as 4% concentration with air. That's low.
 
Hydrogen's low molecular weight makes it the lightest gas around. This was capitalized during the second to last turn of the century, where mighty Zeppelins pushed through the sky like herds of giant sky manatees.
 

http://smhttp.41037.nexcesscdn.net/80153AD/magento/media/catalog/product/cache/1/thumbnail/750x/17f82f742ffe127f42dca9de82fb58b1/m/i/misc156_2.jpg
Large enough to fit Colli-man's collection of miss-matched socks
 
Germany loved these guys, and for a while they were all the rage in luxurious travel. Indeed, it was certainly the 20th century now! We had Airships, the Haber Process that was fueling an industrial revolution, and all of physics was completely solved! Thanks, Maxwell!
 
(And then came the ultraviolet catastrophe, but that's another topic.)
 
However, I mentioned above that hydrogen is extremely flammable at even very low concentrations within air. This fact really sunk the airship industry with a certain spectacular disaster.
 

http://www.hipstersofthecoast.com/wp-content/uploads/2013/06/hindinburg-crashing-burning-640x420.jpg
German Engineering, or Masonic Zion plot?
 
It's easy to skip over this picture entirely. We've all seen it so many times (Unless you're one of my tutoring students, who look at me like I've got two heads when I mention it. “The hinda-what?”).
 
But, this was the end of an era. Static charges ignited the hydrogen sacks that kept the big rigid frame afloat. And though we could have used Helium, a much more stable gas, the damage was done. No one would step foot near a rigid airship again.
 
(Also our world's supply of Helium is finite and diminishing very very quickly. It would be wasted in airships. But again, another topic another time)
 
Let's get back to the Hydrogen Fuelcell. What exactly is it, and how does it work?
 
The basic model is shown below.
 

https://upload.wikimedia.org/wikipedia/commons/thumb/6/63/Proton_Exchange_Fuel_Cell_Diagram.svg/2000px-Proton_Exchange_Fuel_Cell_Diagram.svg.png
 
This diagram is for a Proton Exchange Fuel Cell. The proton here is simply a hydrogen that's been stripped of its single electron. A fuel cell works by having very special membranes carefully constructed to permit the passage of a positively charged ion, but not the negatively charged electron. This travels through another path, leading to a voltage across the cell. This voltage can be used to power any electrical device.
 
This is an oversimplification of how the device works, but it's a start.
 
The benefits of such a device include the shear efficiency that it can have. When properly insulated and owing to proper low-resistance connections, these devices are pushing out efficiencies twice that of internal combustion engines. Which, despite what many places attempt to sell you, are actually quite thermodynamically efficient. These proton based fuel cells have great cold-start characteristics and energy density. Their outputs can actually be very high.
 
Indeed, these fuel cells are efficient at all power outputs as well. Their efficiency does not vary with flow of fuel source either.
 
Their temperatures can be as low as 80 degrees C. However, usually they are kept above 100 degrees C because steam is far more manageable than liquid water byproduct.
 
So with all of this information, you're probably wondering why haven't we started putting these into all sorts of places. This post is about personal vehicles, however, and I'll get right back to that.
 
No. I disagree completely with them being used in personal vehicles.
 
While I love fuel cells as a power device, their use in personal vehicles is greatly limited. One of the biggest engineering hurdles is the flammability and storage of pure hydrogen. Since hydrogen has such a low molecular weight, to obtain a large enough amount to power a personal vehicle would require a very high pressure container. If you remember back to your Chemistry classes in high school, you may remember the Ideal Gas Equation. Hydrogen is pretty close to an Ideal Gas. As close as you'll get, really. The Ideal Gas Law, in actual use, is only about 84% accurate when used to guess thermodynamic systems. For hydrogen it's much higher.
 
PV=nRT, where n is the number of moles. Keeping everything but Pressure and number of moles the same, to increase the number of moles directly increases the pressure. And H2, having a molecular weight of 2 Grams per Mole, would require a ton of moles to get a decent amount of the gas.
 
A very high pressure container of pure hydrogen gas in a vehicle that routinely travels at 70 mph. Which is statistically guaranteed to be in an accident in its lifespan.
 
The Germans are watching this and going “Nein Nein Nein!”
 
http://lmgtfy.com/?q=how+many+car+crashes+per+day+in+the+US
 
According to this nifty search, over 3,000 people die per day in the US due to vehicular collisions. Ouch. 
 
However, this issue is the first to be solved. The introduction of Metal Hydrides have solved the storage issues. Metal Hydrides act as chemical sponges for Hydrogen gas (H2), binding the molecules inside their chemical structure. These metal hydrides are usually used as powders, where the hydrogen is then pushed through to store. To release the hydrogen, the metal hydride must be heated. The rate of diffusion is directly related to the temperature at which the metal hydride is heated, and thus the fuel rate into the fuel cell can be varied by varying the temperature of the metal hydride.
 
Metal hydrides can absorb 2 to 10% H2 usually, but better compounds are being produced to increase the number.
 
https://en.wikipedia.org/wiki/Metal_hydride_fuel_cell
 
This is good, because it gives us a safe way to store hydrogen gas for fuel cells.
 
This is bad, because the fuel delivery rate is much lower, and metal hydride fuel cells are, at their very best, 1/4th as powerful as their PEM brothers. At worst, they are 1/50th.
 
But this is the best we can do in a vehicle. No one wants pressurized hydrogen canisters on the highways. Hell, most of the time you need special clearance and big signs to transport the stuff. And imagine the safety concerns for the EMTs and Paramedics during a car crash. Even if the tank isn't ruptured, no EMT or Paramedic would risk their lives until the wreckage was cleared.
 
When I was going through my EMT training, they made it very clear that it doesn't matter if people are bleeding out in front of you. If you go in while it's still dangerous, you're only being a liability to your fellow EMTs, Firefighters, and police.
 
But let's ignore the low power outputs of these MH Fuel Cells. What other issues do we have?
 
Well, the fuel cell itself must be created using some very interesting techniques and materials. The biggest expense would be the platinum. Other catalysts are needed as well. As well as a very special proton-permeable membrane.
 
To function, the membrane must conduct hydrogen ions (protons) but not electrons as this would in effect "short circuit" the fuel cell. The membrane must also not allow either gas to pass to the other side of the cell, a problem known as gas crossover. Finally, the membrane must be resistant to the reducing environment at the cathode as well as the harsh oxidative environment at the anode.
 
This system includes electrodes, electrolyte, catalyst, and a porous gas diffusion layer. The rate of reaction will be dependent also on how quickly the water vapor product can diffuse through the porous material and out of the system. A system can have a lowered efficiency if the fuel cell is too dry or too wet. A balance must be met.
 
And while yes, all of these situations can be worked around, it all comes at a heavy price. Currently we are using 30 grams of platinum in vehicle sized PEM fuel cells. This number will be going down once different catalysts are created, but the cost of these vehicles still pushes up to $50,000. The cost will go down, like any technology.
 
I've yet to speak about where we obtain this hydrogen gas from. The easiest way to obtain hydrogen gas is via the electrolysis of water. H20 + An Electric Current → H2 + O2, essentially (it's not balanced, I know this.)
 
But that electric current must be created as well. This usually comes from the electric grid, which is still, depending on the state, a majority coal-burning.
 
Natural Gas reformation is another way to obtain Hydrogen gas, and is the most common way we currently use. It's the cheapest as well. Synthesis gas, a mixture of hydrogen, carbon monoxide, and a small amount of carbon dioxide, is created by reacting natural gas with high-temperature steam. The carbon monoxide is reacted with water to produce additional hydrogen.
 
The other common ways are via fermentation of biofuel stocks (which is a long process without a great yield) or liquid reforming, which is really unfeasible in large quantities.
 
The only way to obtain large amounts of hydrogen is via natural gas reformation, and that's still technically a fossil fuel source. So why were we going with hydrogen fuel cells again? To rid ourselves of dirty, dirty fossil fuel? Well shit.
 
So to sum this up, the only way to safely use hydrogen as a fuel source in a moving vehicle would be by using metal hydrides, which require energy to access the stored hydrogen. This stored hydrogen flow rate is lower than standard PEMs, and results in a lower voltage, which in turn leads to a lower power output for the vehicle. More research and development must be done to find proper catalysts that can be made at a low cost, and production methods must be worked out to create the membranes more cheaply. All of this is held up by our hydrogen production systems.
 
PEM fuel cell technology is awesome and I love it to death in many many situations. But vehicles isn't one of them.
 
I may read about more advances in the near future that would change my opinion completely, but I would be surprised.
 
Below I've added a problem out of my heat and mass transfer book (Incropera, 7th edition).
 

Very persuasive speech from a Brexiter:

So we're not doing the whole "respect thy elders" thing anymore, I guess.Look, if only geriatric walker-racers voted for Brexit, anti-Brexiters would be saying that they're such evil, racist old people who don't care about the nation's future.
If only young, hip twentysomethings voted for Brexit, anti-Brexiters would be wailing about how stupid young people are.
See the problem?

Well, before you OD on your own smug there, it seems to me that Nigel was saying two things:
 
1. He couldn't guarantee that the NHS would get the extra money.
 
2. If he had been running that ad campaign (he claims he wasn't), he would not have made that claim.
 
I have no opinion on Brexit, but it seems obvious to me that Brexit opponents are simply unable to believe that their enemies are anything but drooling, completely buffoonish troglodytes. If any of you think it's outrageous of me to point this out, please let me suggest that you stop doing it regardless of how you feel, as this is exactly the same attitude that the US gun control lobby has towards the NRA, and the NRA routinely kicks their ass.
 
The media is couching Farage's statements as him being caught in a lie, but a dimwitted stunt monkey could figure out that's horseshit. As on Brexit, I have no opinion of Farage and am kind of only vaguely aware of who the guy is, so for all I know he is probably a gigantic liar (he is in politics after all), but I'm also not an idiot and it's incredibly obvious that the media is lying to me about what he said. The media is saying "Farage is reneging on his promise" when what he actually said was "it was stupid of the campaign (that I didn't run) to promise that, nobody could guarantee that money would go to the NHS specifically".
 
Maybe, anti-Brexiters, you didn't get whomped tonight because the people of the UK are so goddamn stupid they got taken in by a shyster like Farage. Maybe you got whomped because people can smell your bullshit coming a mile away, and when they call you out on it, you dismiss them as illiterate morlocks. So, it may be past time for anti-Brexit folks to start taking their political adversaries seriously, is what I'm saying.

Behold the worst article on the M14 you've ever seen: http://wethearmed.com/rifles/m14-m1a-rifles/
 
Courtesy Oedipus.

"What the Hell is the Point of Interleaved Road Wheels?"
 
More wheels+ more bearings=More money.
 
Look at Nazi Germany as less of a government, and more of a huge ponzi scheme.

I have the following exchange about five times a summer. 
 
*Hiker coming toward me. I'm biking or running*
 
"There's a snake up there, just a heads up."
 
"Did you move it?" 
 
*I get the most "are you fucking insane" look from this guy/girl*
 
"I'm going to take that as a no."
 
*Finds snake, uses small stick to move it from the trail*
 
 
 
On crowded trails, I move snakes. More for their safety than anyone else's. 

*Sadly puts away "1000 and 1 Stokes Flow Funnies" book*

If the Reynolds number is much less than 10, I don't get jokes.

“Again, the swinging has nothing to do with increasing the protection. The arrow will either penetrate or not (my experience is of the arrow penetrating to about the depth of the head) and will transfer momentum as it does so. The swinging will only substantially take place after the penetration event.”
 
  This is your original postulate. You claim that “the swinging” (in regard to the movement of the object that has been struck) has nothing to do with the arrow penetrating.   You've since cleared up a bit of what you have stated. You now say that there wont be an appreciable difference in penetration given a swinging vs stationary object (shield). That the difference would be purely academic, which you could be very correct on! However, you are also correct in your statement that nothing in real life is instantaneous.    Again, true, depending on the relative reference. And in this case, your very point of penetration not being instantaneous is what makes a "swinging" object not be penetrated as far. I'll get to that later on, but I wrote up a bit on momentum and forces in case anybody was interested in getting a summary of Physics 1.    So we’ll first have to get some definitions going.      FORCE: Force is defined in physics as that which tends to change the momentum of a body containing mass. Force is proportional to the rate of change of momentum. That is, Force is the derivative of momentum. SI Units are the Newton   In other words, Force is the product of a constant mass and an acceleration. Acceleration is the change of velocity with respect to a change in time (dV/dt!)  MOME NTUM: Units are Kilogram per meter second (Kg*m)/s. Or, they can be said as Newton-Seconds (The seconds will cancel, since the Newton is a unit of force. In other words, taking a mass and multiplying it by the velocity will give us a momentum. Momentum is a conserved quality, much like Force.   NET FORCE is the total amount of force exerted by a body in motion. It is the change in momentum divided by the change in time. We can actually determine the net force acting upon an object by using force balances and setting a proper coordinate system.    So let’s start by doing some modeling. No, not that kind of modeling, Sturgeon. Put your shirt back on.    We’ll start by modeling an elastic collision. The definition for such is as follows.    An elastic collision is an encounter between two bodies in which the total kinetic energy of the two bodies after the encounter is equal to their total kinetic energy before the encounter. Elastic collisions occur only if there is no net conversion of kinetic energy into other forms.   Let’s assume that we have two objects, on a single dimensional frictionless plane. Object A has a mass of 5 Kg and object B has a mass of 10 Kg.    Object A is moving toward B on this plane at a speed of 1 m/s   Calculating the momentum of A gives us the following    A  = 5 Kg*m/s,    Sadly, they will collide. Not so sadly, they are hypothetical and we can do terrible things to hypotheticals without consequence.    After the collision, we find that the new velocity of block A is -0.2 m/s   Since we know that momentum is a conserved quantity, and there are no other forces, frictional or otherwise, in this 1-D plane, what will happen after they collide?   (Assume right is positive direction and left is negative as you’re looking at the screen) Initial momentum of system = 5 Kg*m/s Pinitial = Ptotal before collision (P here is how we denote momentum PofA + PofB = Ptotal after the collision We can combine them into the following.  5 kg*m/s = 5 Kg * -0.2 m/s + 10 Kg * VfinalB Solving for the final speed of block B after impact, we find it to be  Vfinal for block B is now 0.6 m/s   Newton’s third law tells us that forces acting upon each other are equal yet in opposite directions. So the force on one is equal to the force on the other.    Overall momentum will be conserved.   Let’s look at once more example. What if block B was moving?   Let’s give B a positive velocity of 0.4 m/s.    I don’t know about you guys, but I don’t like it when two things move. How about we adjust our reference frame? Let’s do a moving reference frame. We focus in on block B, which is moving at 0.4 m/s. That means that, to the observer, block B is no longer moving (But we secretly know it is.) But now, Block A appears to be moving slower. In fact, it appears to be moving at 0.6 m/s (1-0.4!). So what kind of momentum are we going to be imparting into block B when they DO collide?   (0.6)(5) = 3 kg*m/s!   So because the second object was moving in the same direction as the initial block, it received LESS momentum! Since mass didn’t change, it is clear that Velocity played a major part.   This is an important consideration we must remember as we move into our next part.   Now that I’ve beaten that to death, let’s talk about what happens with something more tangible. How about an arrow? What if it’s an inelastic collision? First, we’ll define what exactly that means.   An inelastic collision, in contrast to an elastic collision, is a collision in which kinetic energy is not conserved due to the action of internal friction.   So what does any of that mean?     In the most extreme case (which this is), one object completely sticks to another, imparting all of its momentum.   In the case of an arrow penetrating an object, the depth of penetration is function of many different variables. Penetration requires one object to push the particles of another object out of the way. In doing so, the object doing the penetrating experiences many forces. Forces which are dependent on parameters.   (Writing those sentences made me grin with sophomoric delight.)   Material properties of the arrow tip, material properties of the object being struck, momentum of the arrow and the object, frictional forces (Which are tied to material properties), etc.   When an arrow strikes a target in an inelastic collision, the tip doesn’t simply bounce away. The tip of the arrow pushes particles out of the way, and does so based on the arrow’s momentum (along with a butt-ton of other stuff). However, the arrow is equally pushed back against by the object it has struck. In fact, every particle that the arrow is attempting to push away is robbing the arrow of forward momentum.    But it’s not instantaneous. This arresting of the arrow takes time. Not much, but it does.   Kinetic energy is not conserved during an inelastic collision. That’s an important thing to remember. Also, the impulse time is different (aka, longer) during penetration. Forces are active over a longer period (no longer instantaneous, as was the case in elastic collisions) during penetration.   This time difference is what gives rise to the penetration qualities of swinging vs stationary objects.    At the moment the arrow strikes an object to the moment it stops within the object, momentum is exchanged. Within that time frame, the forces acting opposite to the arrow’s forces (friction within the object) create a force that will push a free (aka not stationary) object in the same direction as the arrow.  This acceleration of the second object robs the arrow of forward velocity, as in our second example from above.    If the velocity is lower, the penetration overall is lower. Again, holding all factors constant and only allowing velocity to change, we can build a model to prove this (Don’t make me do this in Matlab, please, I beg of you. It’s the weekend damnit.)   This does not occur in a stationary object, where the friction forces are not split between moving the struck object AND stopping the arrow, in a sense (This is an oversimplification of force diagrams don’t you dare call me out, Collimatrix)   So in summary, there are about 19348 (Rounding) factors that can effect penetration of one object into another. Holding most of them constant and watching how velocity of a penetrating object changes with respect to a reference frame of the struck object will show that allowing the struck object to use part of the force imparted by the penetrating object to begin a positive movement along the same direction as the penetrating object will lower the penetrative distance and still conserve momentum.    Which might be the longest sentence I’ve ever written.      Sources:    http://cpw.state.co.us/documents/hunting/ehu/momentum-kineticenergy-arrowpenetration.pdf https://en.wikipedia.org/wiki/Elastic_collision https://en.wikipedia.org/wiki/Inelastic_collision http://www.physicstutorials.org/home/impulse-momentum/conservation-of-momentum http://www.physicsclassroom.com/class/newtlaws/Lesson-3/Double-Trouble

“Again, the swinging has nothing to do with increasing the protection. The arrow will either penetrate or not (my experience is of the arrow penetrating to about the depth of the head) and will transfer momentum as it does so. The swinging will only substantially take place after the penetration event.”
 
  This is your original postulate. You claim that “the swinging” (in regard to the movement of the object that has been struck) has nothing to do with the arrow penetrating.   You've since cleared up a bit of what you have stated. You now say that there wont be an appreciable difference in penetration given a swinging vs stationary object (shield). That the difference would be purely academic, which you could be very correct on! However, you are also correct in your statement that nothing in real life is instantaneous.    Again, true, depending on the relative reference. And in this case, your very point of penetration not being instantaneous is what makes a "swinging" object not be penetrated as far. I'll get to that later on, but I wrote up a bit on momentum and forces in case anybody was interested in getting a summary of Physics 1.    So we’ll first have to get some definitions going.      FORCE: Force is defined in physics as that which tends to change the momentum of a body containing mass. Force is proportional to the rate of change of momentum. That is, Force is the derivative of momentum. SI Units are the Newton   In other words, Force is the product of a constant mass and an acceleration. Acceleration is the change of velocity with respect to a change in time (dV/dt!)  MOME NTUM: Units are Kilogram per meter second (Kg*m)/s. Or, they can be said as Newton-Seconds (The seconds will cancel, since the Newton is a unit of force. In other words, taking a mass and multiplying it by the velocity will give us a momentum. Momentum is a conserved quality, much like Force.   NET FORCE is the total amount of force exerted by a body in motion. It is the change in momentum divided by the change in time. We can actually determine the net force acting upon an object by using force balances and setting a proper coordinate system.    So let’s start by doing some modeling. No, not that kind of modeling, Sturgeon. Put your shirt back on.    We’ll start by modeling an elastic collision. The definition for such is as follows.    An elastic collision is an encounter between two bodies in which the total kinetic energy of the two bodies after the encounter is equal to their total kinetic energy before the encounter. Elastic collisions occur only if there is no net conversion of kinetic energy into other forms.   Let’s assume that we have two objects, on a single dimensional frictionless plane. Object A has a mass of 5 Kg and object B has a mass of 10 Kg.    Object A is moving toward B on this plane at a speed of 1 m/s   Calculating the momentum of A gives us the following    A  = 5 Kg*m/s,    Sadly, they will collide. Not so sadly, they are hypothetical and we can do terrible things to hypotheticals without consequence.    After the collision, we find that the new velocity of block A is -0.2 m/s   Since we know that momentum is a conserved quantity, and there are no other forces, frictional or otherwise, in this 1-D plane, what will happen after they collide?   (Assume right is positive direction and left is negative as you’re looking at the screen) Initial momentum of system = 5 Kg*m/s Pinitial = Ptotal before collision (P here is how we denote momentum PofA + PofB = Ptotal after the collision We can combine them into the following.  5 kg*m/s = 5 Kg * -0.2 m/s + 10 Kg * VfinalB Solving for the final speed of block B after impact, we find it to be  Vfinal for block B is now 0.6 m/s   Newton’s third law tells us that forces acting upon each other are equal yet in opposite directions. So the force on one is equal to the force on the other.    Overall momentum will be conserved.   Let’s look at once more example. What if block B was moving?   Let’s give B a positive velocity of 0.4 m/s.    I don’t know about you guys, but I don’t like it when two things move. How about we adjust our reference frame? Let’s do a moving reference frame. We focus in on block B, which is moving at 0.4 m/s. That means that, to the observer, block B is no longer moving (But we secretly know it is.) But now, Block A appears to be moving slower. In fact, it appears to be moving at 0.6 m/s (1-0.4!). So what kind of momentum are we going to be imparting into block B when they DO collide?   (0.6)(5) = 3 kg*m/s!   So because the second object was moving in the same direction as the initial block, it received LESS momentum! Since mass didn’t change, it is clear that Velocity played a major part.   This is an important consideration we must remember as we move into our next part.   Now that I’ve beaten that to death, let’s talk about what happens with something more tangible. How about an arrow? What if it’s an inelastic collision? First, we’ll define what exactly that means.   An inelastic collision, in contrast to an elastic collision, is a collision in which kinetic energy is not conserved due to the action of internal friction.   So what does any of that mean?     In the most extreme case (which this is), one object completely sticks to another, imparting all of its momentum.   In the case of an arrow penetrating an object, the depth of penetration is function of many different variables. Penetration requires one object to push the particles of another object out of the way. In doing so, the object doing the penetrating experiences many forces. Forces which are dependent on parameters.   (Writing those sentences made me grin with sophomoric delight.)   Material properties of the arrow tip, material properties of the object being struck, momentum of the arrow and the object, frictional forces (Which are tied to material properties), etc.   When an arrow strikes a target in an inelastic collision, the tip doesn’t simply bounce away. The tip of the arrow pushes particles out of the way, and does so based on the arrow’s momentum (along with a butt-ton of other stuff). However, the arrow is equally pushed back against by the object it has struck. In fact, every particle that the arrow is attempting to push away is robbing the arrow of forward momentum.    But it’s not instantaneous. This arresting of the arrow takes time. Not much, but it does.   Kinetic energy is not conserved during an inelastic collision. That’s an important thing to remember. Also, the impulse time is different (aka, longer) during penetration. Forces are active over a longer period (no longer instantaneous, as was the case in elastic collisions) during penetration.   This time difference is what gives rise to the penetration qualities of swinging vs stationary objects.    At the moment the arrow strikes an object to the moment it stops within the object, momentum is exchanged. Within that time frame, the forces acting opposite to the arrow’s forces (friction within the object) create a force that will push a free (aka not stationary) object in the same direction as the arrow.  This acceleration of the second object robs the arrow of forward velocity, as in our second example from above.    If the velocity is lower, the penetration overall is lower. Again, holding all factors constant and only allowing velocity to change, we can build a model to prove this (Don’t make me do this in Matlab, please, I beg of you. It’s the weekend damnit.)   This does not occur in a stationary object, where the friction forces are not split between moving the struck object AND stopping the arrow, in a sense (This is an oversimplification of force diagrams don’t you dare call me out, Collimatrix)   So in summary, there are about 19348 (Rounding) factors that can effect penetration of one object into another. Holding most of them constant and watching how velocity of a penetrating object changes with respect to a reference frame of the struck object will show that allowing the struck object to use part of the force imparted by the penetrating object to begin a positive movement along the same direction as the penetrating object will lower the penetrative distance and still conserve momentum.    Which might be the longest sentence I’ve ever written.      Sources:    http://cpw.state.co.us/documents/hunting/ehu/momentum-kineticenergy-arrowpenetration.pdf https://en.wikipedia.org/wiki/Elastic_collision https://en.wikipedia.org/wiki/Inelastic_collision http://www.physicstutorials.org/home/impulse-momentum/conservation-of-momentum http://www.physicsclassroom.com/class/newtlaws/Lesson-3/Double-Trouble

“Again, the swinging has nothing to do with increasing the protection. The arrow will either penetrate or not (my experience is of the arrow penetrating to about the depth of the head) and will transfer momentum as it does so. The swinging will only substantially take place after the penetration event.”
 
  This is your original postulate. You claim that “the swinging” (in regard to the movement of the object that has been struck) has nothing to do with the arrow penetrating.   You've since cleared up a bit of what you have stated. You now say that there wont be an appreciable difference in penetration given a swinging vs stationary object (shield). That the difference would be purely academic, which you could be very correct on! However, you are also correct in your statement that nothing in real life is instantaneous.    Again, true, depending on the relative reference. And in this case, your very point of penetration not being instantaneous is what makes a "swinging" object not be penetrated as far. I'll get to that later on, but I wrote up a bit on momentum and forces in case anybody was interested in getting a summary of Physics 1.    So we’ll first have to get some definitions going.      FORCE: Force is defined in physics as that which tends to change the momentum of a body containing mass. Force is proportional to the rate of change of momentum. That is, Force is the derivative of momentum. SI Units are the Newton   In other words, Force is the product of a constant mass and an acceleration. Acceleration is the change of velocity with respect to a change in time (dV/dt!)  MOME NTUM: Units are Kilogram per meter second (Kg*m)/s. Or, they can be said as Newton-Seconds (The seconds will cancel, since the Newton is a unit of force. In other words, taking a mass and multiplying it by the velocity will give us a momentum. Momentum is a conserved quality, much like Force.   NET FORCE is the total amount of force exerted by a body in motion. It is the change in momentum divided by the change in time. We can actually determine the net force acting upon an object by using force balances and setting a proper coordinate system.    So let’s start by doing some modeling. No, not that kind of modeling, Sturgeon. Put your shirt back on.    We’ll start by modeling an elastic collision. The definition for such is as follows.    An elastic collision is an encounter between two bodies in which the total kinetic energy of the two bodies after the encounter is equal to their total kinetic energy before the encounter. Elastic collisions occur only if there is no net conversion of kinetic energy into other forms.   Let’s assume that we have two objects, on a single dimensional frictionless plane. Object A has a mass of 5 Kg and object B has a mass of 10 Kg.    Object A is moving toward B on this plane at a speed of 1 m/s   Calculating the momentum of A gives us the following    A  = 5 Kg*m/s,    Sadly, they will collide. Not so sadly, they are hypothetical and we can do terrible things to hypotheticals without consequence.    After the collision, we find that the new velocity of block A is -0.2 m/s   Since we know that momentum is a conserved quantity, and there are no other forces, frictional or otherwise, in this 1-D plane, what will happen after they collide?   (Assume right is positive direction and left is negative as you’re looking at the screen) Initial momentum of system = 5 Kg*m/s Pinitial = Ptotal before collision (P here is how we denote momentum PofA + PofB = Ptotal after the collision We can combine them into the following.  5 kg*m/s = 5 Kg * -0.2 m/s + 10 Kg * VfinalB Solving for the final speed of block B after impact, we find it to be  Vfinal for block B is now 0.6 m/s   Newton’s third law tells us that forces acting upon each other are equal yet in opposite directions. So the force on one is equal to the force on the other.    Overall momentum will be conserved.   Let’s look at once more example. What if block B was moving?   Let’s give B a positive velocity of 0.4 m/s.    I don’t know about you guys, but I don’t like it when two things move. How about we adjust our reference frame? Let’s do a moving reference frame. We focus in on block B, which is moving at 0.4 m/s. That means that, to the observer, block B is no longer moving (But we secretly know it is.) But now, Block A appears to be moving slower. In fact, it appears to be moving at 0.6 m/s (1-0.4!). So what kind of momentum are we going to be imparting into block B when they DO collide?   (0.6)(5) = 3 kg*m/s!   So because the second object was moving in the same direction as the initial block, it received LESS momentum! Since mass didn’t change, it is clear that Velocity played a major part.   This is an important consideration we must remember as we move into our next part.   Now that I’ve beaten that to death, let’s talk about what happens with something more tangible. How about an arrow? What if it’s an inelastic collision? First, we’ll define what exactly that means.   An inelastic collision, in contrast to an elastic collision, is a collision in which kinetic energy is not conserved due to the action of internal friction.   So what does any of that mean?     In the most extreme case (which this is), one object completely sticks to another, imparting all of its momentum.   In the case of an arrow penetrating an object, the depth of penetration is function of many different variables. Penetration requires one object to push the particles of another object out of the way. In doing so, the object doing the penetrating experiences many forces. Forces which are dependent on parameters.   (Writing those sentences made me grin with sophomoric delight.)   Material properties of the arrow tip, material properties of the object being struck, momentum of the arrow and the object, frictional forces (Which are tied to material properties), etc.   When an arrow strikes a target in an inelastic collision, the tip doesn’t simply bounce away. The tip of the arrow pushes particles out of the way, and does so based on the arrow’s momentum (along with a butt-ton of other stuff). However, the arrow is equally pushed back against by the object it has struck. In fact, every particle that the arrow is attempting to push away is robbing the arrow of forward momentum.    But it’s not instantaneous. This arresting of the arrow takes time. Not much, but it does.   Kinetic energy is not conserved during an inelastic collision. That’s an important thing to remember. Also, the impulse time is different (aka, longer) during penetration. Forces are active over a longer period (no longer instantaneous, as was the case in elastic collisions) during penetration.   This time difference is what gives rise to the penetration qualities of swinging vs stationary objects.    At the moment the arrow strikes an object to the moment it stops within the object, momentum is exchanged. Within that time frame, the forces acting opposite to the arrow’s forces (friction within the object) create a force that will push a free (aka not stationary) object in the same direction as the arrow.  This acceleration of the second object robs the arrow of forward velocity, as in our second example from above.    If the velocity is lower, the penetration overall is lower. Again, holding all factors constant and only allowing velocity to change, we can build a model to prove this (Don’t make me do this in Matlab, please, I beg of you. It’s the weekend damnit.)   This does not occur in a stationary object, where the friction forces are not split between moving the struck object AND stopping the arrow, in a sense (This is an oversimplification of force diagrams don’t you dare call me out, Collimatrix)   So in summary, there are about 19348 (Rounding) factors that can effect penetration of one object into another. Holding most of them constant and watching how velocity of a penetrating object changes with respect to a reference frame of the struck object will show that allowing the struck object to use part of the force imparted by the penetrating object to begin a positive movement along the same direction as the penetrating object will lower the penetrative distance and still conserve momentum.    Which might be the longest sentence I’ve ever written.      Sources:    http://cpw.state.co.us/documents/hunting/ehu/momentum-kineticenergy-arrowpenetration.pdf https://en.wikipedia.org/wiki/Elastic_collision https://en.wikipedia.org/wiki/Inelastic_collision http://www.physicstutorials.org/home/impulse-momentum/conservation-of-momentum http://www.physicsclassroom.com/class/newtlaws/Lesson-3/Double-Trouble

Oh I'm just dying to hear, Tox, how arrows and shields don't obey conservation of momentum.

It's the fantasy of getting to kill all of those around you without the repercussions. 
 
And those with this fantasy are usually weak. 
 
So they empathize with the inept protagonists of zombie stories.