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Comment How efficient is hydrogen really? (Score 3, Interesting) 199

OK. How efficient is hydrogen, really? Shout out to all of the chemistry majors out there who might answer this.

One of the reasons that fuels work, from my understanding, is that you start with a small number of molecule, combust them, and get a larger number of molecules with more heat. The heat increases the pressure, and the increase in the number of molecules increases the pressure.

Example: combustion of alcohol:

C2H6O +3O2 --> 3H2O + 2CO2

We start with four molecules on the left, and get five molecules on the right. Even if the reaction was not exothermic, we would still get a pressure increase good for pushing a piston.

Now, when we burn hydrogen, we get a decrease in the number of molecules (goes from three down to two):

2H2 + O2 --> 2H2O

So, yes, we get increased pressure due to heat production, but we get decreased pressure due to fewer molecules.

So, I guess that my question is: when burning a fuel, how much pressure created is due to the typical increase in molecules, and how much pressure is due to heat?

Comment Re:Johnson and anti-incumbent (Score 1) 382

no, that's pretty much what the bible says to do...

Yes, I should listen to somebody who has probably spent many, many minutes learning about the bible....

John chapter 8. Some guys bring a woman to Jesus to see if he is willing to stone her. His response? "Let any of you who is without sin be the first to throw a stone at her." Needless to say, the woman lived.

That is called the "New Testament" and covers the life of Jesus and shortly afterwords.

Comment Re:Asinine. (Score 1) 438

I say, make guns like driving, but on a "shall issue" permit requiring a reasonable proficiency test.

So, my drivers license is good in all 50 states. If I get a concealed permit, that should be good in all 50 states too, right? If you want it more like driving, then you should not get to pick and choose which parts of that analogy you like.

Comment Re:Johnson and anti-incumbent (Score 2) 382

against abortion

Thou shalt not kill

Those two are kind of the same thing...

Plus, the real quote is usually translated as "You shall not murder"(hebrew "rasah") which is different from kill. If somebody is trying to kill you, the bible does not say that you cannot defend yourself, which goes well with gun rights.

Comment Re:MS Hates Linux (Score 1) 484

How many of those 33% would go and buy the PC through the Microsoft Store? Why wouldn't they just buy it from Lenovo if they don't want to run Windows?

The summary explicitly stated "Best Buy." If you are going to purchase a laptop and don't want to wait for shipping, going to a place like Best Buy is certainly not unreasonable (especially since they price match placed like Amazon). Having purchased what was believed to be an "ordinary" PC and not being able to install the OS of choice is, understandably, a bit of a shock.

To people who have strong feelings about Best Buy: don't read this as an invitation to bash/praise them. This comment is simply that the machine apparently was not purchased from Microsoft, no handcuffs were not expected to be included with the purchase.

Comment Re:So in other words it's used and is useful (Score 1) 248

But they said it's a "barometric vent"; not a barometer. Could it just be a hole to make sure the internal and external pressure are the same?

I remember when the waterproof Yaesu VX-7 radio came out (hand-held amateur radio transceiver), and it had a problem with being too sealed.. The problem with anything that is waterproof and has a speaker and/or a microphone is that the pressure on the inside can be very different from the pressure on the outside. If you change altitude, you will find that the pressure difference inside can press on the speaker diaphragm and/or microphone diaphragm. This limits the diaphragm travel, and will result in distorted audio. When this happened on the VX-7, the users discovered that they could crack open the battery case to "burp" the unit, restoring normal audio (at least until they changed elevation again). The eventual solution from the manufacturer turned out to be (from what I understand) to actually put a hole in the case and cover it with Gore-Tex. Water still stays out, but enough air can get through to equalize the pressure.

Since the iPhone has both speakers and microphones, something like this is needed if you really want to make it waterproof. Since the interior then has the same pressure as the outside, that makes it easy to drop a barometric sensor anywhere there is space on the board.

Comment Re:Incitement in Hebrew (Score 1) 232

The problem is that the "state that stole their land" is actually a state. All Muslims around Israel only want peace -- by killing every Jew...

Let me list some surrounding Muslim countries:
* Lebanon
* Jordan
* Syria
* Iraq
* Egypt
* Lybia
* Kuwait
* Turkey
* Iran

Next, let me list every single Jewish country in the world:
* Israel

Yeah, a very short list.

Do you even know HOW Israel came into possession of the "occupied territories?" Israel was surrounded by armies on all sides ready to invade, and got their butts kicked.

Let me put it this way. If Canada and Mexico tried to invade the USA, could you blame us if we took part of both as a "buffer zone?" Also, if people in those areas were routinely launching unguided rockets at us, and having their citizens routinely commit mass murder against our citizens, don't you think that trying to stop the attacks would be a priority?

Comment Re:Incitement in Hebrew (Score 2, Interesting) 232

You can bet a Jewish-founded and Jewish-funded site is going to do zero in regards to Hebrew language incitement against the Palestinians or Iranians or anyone else out of favor there.

I hate replying to an AC, but can you show me some Jewish incitement?

The Palestinians actually had a hate-based children's show called Tomorrow's Pioneers. Yes, this was a show aimed at small children, and tried to teach them that killing Jews is a good thing. Show me ANYTHING comparable that the Jews have done.

There is also a "holiday" called Quds day this is sort of a Muslim "we hate the Jews" celebration. Once again, show me an Israeli holiday focused on killing Muslims.

Comment Re:Ugh, Sometimes I hate people (Score 5, Informative) 308

As an EE, I have some experience with this. I really do digital logic chip design, and leave the design of the IO pins to the analog guys (and I am NOT an analog guy)...

However, pins are designed to dissipate excess charge using the "human body model." The specification is charging a small capacitor to a few thousand volts and dissipating that into a pin. Since the capacitance is small, the total amperage is very small. There are zener diodes built into IO pads that can handle this small amount of current. An ESD event will only last for the barest fraction of a second. Now, if you actually intentionally put too much voltage across pins for a prolonged period of time, I can easily imagine those zener diodes dying. Once that happens, the voltage will start to play merry hell with the logic.

I also did some government (military) work a decade ago. With those systems, you generally hardened them against EMP pulses (don't want a nuke taking down your electronics), so we used something called "transorbs.". Basically, these are big, beefy external zener diodes that can clamp this type of event. HOWEVER, from what I recall, those diodes put too much capacitance on the line, which would do very bad things to high-speed data lines, such as the ones found in USB data lines. Transorbs are great for things like low-speed serial port lines (which explains standards like MIL-STD-1553. I do not know if transorbs have improved much (not done that sort of thing for 10 years), but these are the types of problems you have to face when dealing with something like this -- the devices needed to protect your USB ports might just make your USB ports unusable.

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