big314mp

The earth is attracted to the sun. If there were no attraction between the earth and the sun, then the earth would not stay in orbit. Imagine a ball on a string. If you swing the ball around in the air, it goes (more or less) in a circle. The string represents gravity, and you would represent the sun. Should there be no gravitational attraction (say, we cut the string), the ball (earth) flies off in a straight line. Laugh out loud at the coincidences of life:-p

All of these are from wikipedia: BP of silica: 2230C BP of lime: 2850C BP of iron: 2862C BP of nickel: 2913C BP of alumina: 2980C BP of magnesia: 3600C Temperature at Surface of the Sun: ~5500C IMO, the sun wins. While looking up this data, I found this site, which has some pretty good laughs: http://www.thesurfaceofthesun.com/

Yes, very much. Thanks!

I understand the mathematics behind it (somewhat better, now that you have put it in sigma notation), but the notion of a body experiencing acceleration in two different directions seemed nonsensical to me, so I assumed it was just an artifact of the equation, if that makes any sense. I see that they are equivalent, but I think I'll stick with thinking in terms of forces. Thanks for the lesson though!

Generally when speaking of elements, one refers to how a pure sample would exist at standard state. A bunch of lone I atoms does not exist at standard conditions, so it is not considered the "base form", for lack of better terminology. Consider a block of copper. All of the atoms share metallic bonds with each other, so do we only consider copper gas elemental copper? Consider diamond. Do we consider diamond not elemental carbon? The latter phenomenon is known as Allotropy: http://en.wikipedia.org/wiki/Allotropes

I did in fact read your link, and my post was basically my best understanding of your link + what I have learned in physics. I think I misunderstood your point on this: "If there is force, there is acceleration." I interpreted force as total force, and acceleration as change in velocity. Thank you for clarifying.

Now I'm confused. I was under the impression that acceleration was rate of change of velocity. Therefore, with no change in velocity, there is zero acceleration. F=ma. If a is zero, this implies that F is zero. Since F is the net force on the object, then this implies that there is zero net force on the object. Zero net force can be achieved by zero total forces acting on the object, or all forces acting on the object cancel out. A person standing on a scale falls into the latter category. The force applied by the trap door and scale is the same as the force applied by gravity, so they cancel out. Should the trap door open, this counter force is gone. Then there is a net force on the object and the object experiences acceleration. The point of all of that was that it is logical to consider forces to cancel with each other. I'm lost when you speak of canceling accelerations of objects, as this seems to imply an object trying to accelerate in two different directions. Basically, if we made gravity go away, would the counter acceleration launch the person into space? Obviously not. We may be saying the exact same thing, in which case this is all moot.

Favorite part was the end of the debate, when Brokaw broke off what he was saying, because one of the candidates got in the way of the teleprompter. "Uh, guys. I can't see my script, so if you could just move a little?" This debate was hilarious. Trains lost wheels, jello was nailed to walls, the federal deficit was compared to the candidates overrunning their time limits...

Try modeling using a MOSFET driver instead of just a comparator. MOSFETs are voltage driven, so it looks like you aren't applying sufficient voltage to the gate, and the MOSFET is acting as an amplifier. I think something is wrong with your model though, as the gate switches on once the gate voltage reaches a certain level. Switching speed is (mostly) a function of amps applied and the gate capacitance. As the gate capacitance of MOSFETs is usually pretty low, they switch fairly quick. Someone with more electronics experience should post also, as I am definitely not an expert on this stuff.

It's still a win in my book if I can hear up that high and you can't I had to google "EPROM" as I had never heard of it before. Nifty stuff.

If you look at the mechanism of a fischer esterification, the carbonyl is actually protonated first. http://en.wikipedia.org/wiki/Fischer_esterification

Classical music is what they use at our downtown library. I think they are referring to this: http://en.wikipedia.org/wiki/The_Mosquito I haven't actually heard it, but I played the frequency at home once, and it was pretty damn annoying. My brother came down from upstairs and complained about it. My parents in the same room didn't hear a thing. That last bit was pretty cool, IMO, but the sound itself sucks. Granted, I think I played it rather loudly compared to the levels it is usually played at.

In carbonyl groups, the oxygen is double bonded to the carbon. There are two resonance structures for this. The first has a double bond, and no formal charges. The second has a single bond, a formal minus on the oxygen, and a formal plus on the carbon. This second structure is less favored than the first, due to the presence of the formal charges. What those two resonance structures tell, is that the pi bond between the carbon and the oxygen is polarized towards the oxygen, thereby putting somewhat of a minus charge on the oxygen. Since this is only a partial minus charge, adding another bond will put a formal plus charge on the oxygen (or on the carbon if you move the pi electrons in the double bond to the oxygen). This type of structure is unfavorable, so the carbonyl oxygen is not nucleophilic.

(tax rate + 1) x (cost of service) = (total cost paid) In your case specifically: (.07 + 1) x (unknown) = 200 200/1.07 = $186.91 (rounded down to nearest penny) 200-186.91 = $13.09

The carbonyl oxygen would technically be more nucleophilic, as it has more electron density. However, it really isn't a very good nucleophile at all because the negative charge is distributed via resonance. Something like an alkoxide (RO-, the conjugate base of an alcohol) is a much better nucleophile as the negative charge is all concentrated on one atom.

I extend my humblest apologies for him . A NaOH + HCl titration, for the 1:1 mole ratio? Calculate the moles of zinc (or copper) in a penny, via dissolving the inside out with HCl, and then reweighing? Do baking soda + acid, and then use the volume of the resulting gas to calculate the starting number of moles of reactants?

Yes. it would be a hypervalent structure, as the sulfur has six bonds to it. Since each bond is composed of 2 electrons, the sulfur has 12 electrons around it.

This solution isn't great, but here goes: Dissolve a sample of the starch/flour in water, break it down with an enzyme such as amylase, and titrate with benedict's reagent. Perhaps you could also dissolve some starch in water, and then measure it's freezing point, to determine the molarity. I looked up (on wikipedia) that all purpose flour is about 11% gluten (I'm assuming by weight). I think that would be needed to do maths, as gluten wouldn't be caught by the first test, and its not particularly soluble in water either. Both methods would be horribly inaccurate, but they may work. My roommate now suggests that your students bring in guacaMOLE

I don't see how this works, as the hot water must become cold water before it freezes, right? Basically: hot water -> cold water -> ice vs. cold water -> ice The cold water just has to freeze, whereas the hot water must first cool down then freeze . Thanks!

CaptainPanic has a good point, which led me to another idea: What if instead of trying to contain the radionuclides, you dumped them into the upper atmosphere, so that they scatter over a huge area, so the localized effect is negligible. It would still be a PR disaster, but perhaps clean up costs could be avoided.

Since the article suggests applications in radar, I don't think it works like an EMP bomb. If it was for something like radar defense, it would have to be reusable.

I'd imagine that the molecular weight of flour would be fairly constant (mostly starch). Same for butter (mostly fat). It would be a range of fats, and a range of starches, but it would probably average out to something relatively constant. That's most of what you need for cookies. As to what those molecular weights are, that's a different story. I have no idea.

Do it once per student . My roommate suggested doing some cooking with all ingredient amounts in moles.

Perhaps a board of some sort? I'm imagining a hill that one could sled down.

Three things: First, unless one already has additional unused space in the house, you may not see too much of a gain. What I'm saying is, moving to a smaller house may save more money than having a garden in the extra space. Of course, if this isn't an option, then run with the idea. Second, perhaps you could have those solar tube things to channel in sunlight when it is sunny, in order to save some on electric costs? Also, maybe solar water heating + fluorescent lights + small heater (for when it isn't sunny) may be more efficient? Third, where I live, gas is (I think) slightly cheaper than electric per unit of energy, so it is actually cheaper for us to use gas heating rather than electric heating (or incandescent lights, for that matter). Maybe things are different elsewhere, but that may be a limiting factor. I suspect that if cheap electricity becomes common, or the price of CNG goes up (say if it is used in cars or runs low or any number of other things) then this becomes a non-issue. And I just thought of this: You will have to swap to CFL bulbs in the summer, as you won't need to heat the house.