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Yer, tree, too much homework in one day? x=0, y=0 is one solution. x=1, y=0 is another solution. I don't believe there are any other real solutions to this equation.

NAV doesn't include a firewall, NIS (Norton Internet Security) does. So NAV wouldn't be blocking your FTP. I'm still on SP1, and I am aware that SP2 is very different when it comes to the firewall, so I can't really help you. However FTP must be documented somewhere, try the Windows help options. Also just try browsing around all the options related to the firewall, it should be there somewhere! Maybe under 'exceptions' or 'rules' or some such. http://support.microsoft.com/kb/842242 And click: Enable programs by using Windows Firewall http://technet2.microsoft.com/WindowsServer/en/library/dce3dc46-2581-472b-9f75-54149063c8811033.mspx?mfr=true Click on: I cannot get my FTP program to work with Windows Firewall Also from browsing through a few things like that you might want to look into PASV FTP, which I think is what your problem may be centered around.

You need to use the formula: amount (moles) = molecular mass / mass of the molecule You know it's a 1:1 ratio. That's a molar ratio. That is, you want 1 mole of KCl to react with 1 mole of NaNO3. In the reaction: 2H2 + O2 --> 2H2O It's a 2:1 ratio of hydrogen to oxygen. So you want 2 moles of hydrogen for every mole of oxygen. "The approx molecular mass of KCl=74 and NaNO3=85" I'll take your word for that... now you want a ratio of how much mass to how much mass. To start off with we have a molar ratio of 1:1. As: amount = molecular mass / mass the molar ratio could be written as: (RFM is relative formula mass, it's the same as molecular mass) (RFM / mass) : (RFM / mass) (74 / massKCl) : (85 / massNaNO3) Moving the 85 over to the other side: (74 / 85*massKCl) : (1 / massNaNO3) 74/85 = 0.87 (0.87 / massKCl) : (1 / massNaNO3) flipping both the fractions over: (massKCl / 0.87) : (massNaNO3 / 1) (massNaNO3 / 1) is just (massNaNO3) (massKCl / 0.87) : (massNaNO3) So you take the mass of KCl you have and divide it by 0.87 to get the mass of the NaNO3. Or... Moving the 0.87 over gives: (massKCl) : (0.87*massNaNO3) So take the mass of the NaNO3 and multiply it by 0.87 to get the mass of KCl you need. Hopefully that helps.

Well, I assume you're talking about two waves completely constructively superimposing... if they were going along a single string then for the 2nd wave to catch up with the 1st it would have to be travelling faster. Consequently the two waves would not constructively superimpose, as one wave overtook the other the superposition would vary, ie. it would not always be constructive. Which brings us back the Y-setup. Ignoring all proportionality constants:energy = tension = (amplitude)² So if the input energy per slinky is 1J and you have two slinkies then total input is 2J. Also the tension in each slinky is 1N. When the pair of slinkies join to the single slinky, as m4rc said; "the tension in the single slinky is twice that in each slinky of the pair". The tension doubling seems a logical step, as it's twice the force, 1N from each slinky provides a net force of 2N. Therefore the tension in the single slinky is 2N. This would make the energy out 2J. All good so far, however now we come onto the amplitudes. Originally there were 2 waves of energy 1J and 1J. By square rooting this energy we get the amplitude of the two original waves, which are 1 and 1. However at the end of the experiment we have one wave of energy 2J. By square rooting this energy we get the amplitude of the single and final wave, which is [math]\sqrt{2}[/math]. Having an amplitude of [math]\sqrt{2}[/math] had crossed my mind before, but it was only rereading m4rc's: energy [math]\propto[/math] tension [math]\propto[/math] (amplitude)² that made me think along those lines further. What do you think of this?

Is this for Service Pack 1 or 2? There's a big difference. Do you have another firewall such as ZoneAlarm or Norton? If so then you can just turn off the Windows one, as ZA or Norton are good enough on their own.

You can get two waves to superimpose on a string easily... Get two people to hold opposite ends of a piece of string and wave it up and down. If they do it well then you will get the two waves superimposing... standard demonstration for nodes, antinodes & standing waves. (Alternatively you could get a vibrator and fix the other end of the string to something stationary.)

[edit] I thought I had a solution, it seems I've just re-proved the violation of the conservation of energy, which sucks because it's crap, I put all of this in grey. I have got some more ideas, including what I think is the real answer in black below. So you can skip the grey if you want! We know the power of the wave is proportional to the amplitude squared. For the sake of this explanation I'm going to assume that the proportionality constant is 1, that is, power equals amplitude squared. Follow this through the and constant would cancel anyway, it's just easier omitting it for now. Initially lets deal with the amplitudes within the system. So you have your Y-formation with two waves, each of amplitude 2, along the two branches of the Y. When these waves reach the middle of the Y formation half of the wave bounces back towards the source and the other half combines to form the tail of the Y. The blue shows what happens after the wave reaches the mid point of the Y. Half of the two combining waves reflect back, and the other half of both of them combine. As each input wave has an amplitude of 2, when the wave reached the mid point of the Y half the wave bounces back with amplitude of 1, and the part of the wave continuing along the tail has amplitude 1. However there are two waves constructively superimposing, giving an actual amplitude of 2 along the tail. OK, so we have two input waves, each of amplitude 2. Amplitude squared is the power input, 2²=4, and there's two inputs, so total power input is 2*4=8. And now lets look at the output, represented by the blue lines in the diagram. We have an amplitude of 1 at source 'a' and 'b' and an amplitude of 2 at 'c'. 1²+1²+2²=6 6 (out) doesn't equal 8 (in)... That's not meant to happen. ====================== Useful part of the reply below ====================== The whole Y-formation setup seems to be over complicating the issue, mainly because how the wave behaves on within the Y setup is not easy to predict. The wave does not totally superimpose, and it's not a simple 50/50 split at the mid point. The behaviour of the waves should be able to be predicted, but I do not know how. Maybe the energy splits and not the amplitude, or maybe, taking into account factors such as tension and other resistive forces, you end up with a complex answer which we won't guess just by looking at it. So I went back to look at the question, and to calculate the answer without the Y experiment. OK, so we have two waves, each of amplitude 1 travelling along a string (black). For simplicity of thinking lets assume the waves constructively interfere. Producing a wave of amplitude 1+1=2 (blue). The average power of the two waves could be considered as the power when the two waves are superimposed. If power equals amplitude squared (I'm ignoring the proportionality constant for simplicity), then the power of one wave is 1²=1 and the power of the superimposed wave is 2²=4. As 4 is 4*1 the average power, or the power of the two waves superimposed, is 4 times the power of one wave. My question is this: if these two waves were to destructively interfere then where would the energy go?

He was, but most of what he said was correct. Most of the "quack" has been formed by people today taking and corrupting his ideas, claiming them as "free energy" or some other impossible theory. He discovered AC (alternating current), which is how all mains electricity is produced, transmitted and used* today. He developed the first radio and did a lot of work with magnetic (and electric) fields. The unit of magnetic flux density is the Tesla. As previously mentioned he also invented the Tesla coil. He also did work on transformers, which as you know are found commonly in every household today. He did have some "wonky" ideas, but they've been made "wonkier" by people who do not fully understand his work, nor physics. At the same time he is, effectively, creator of radios and AC electricity, so he wasn't a complete nutter. *obviously some appliances have a AC to DC converter, but I'm trying to keep it simple!

I'm lost, where's the quote from? Graphite conducts because there are many delocalised electrons between the planes of graphite. As the quote says, as the electrons are situated between the graphite layers or planes it can only conduct along the planes, the electrons cannot easily travel through the layers of carbon atoms. Whereas in a fullerene you have electrons in the middle of a sphere of carbon atoms. How is that, in any way, similar to graphite? My chemistry teacher thinks that trying to get a guest-compound to go inside a fullerene (which would act as the host) would be a good PhD project. He's also interested in what the electrons would do in that situation, as well as where exactly they are in a standard C60 molecule.

No, read what swansont wrote, below. I can't word it better than that.

I think the Your Experiment section should be left for Chemistry only. There are not that many physics experiments discussed here, and those which are posted within the relevant subforum. Having a General > Your Experiment forum is too general and could be confusing. Whereas if a new member came along and saw, under Chemistry, a Your Experiments subforum it would be perfectly clear. However I like the new home page a lot. It put a smile on my face to see it back in place... ok, that's sad isn't it?! But still, it's a great "face" of our community and it looks very impressive.

From years 7 to 11 I had a uniform, then when I moved to the Sixth Form in the school there is no uniform. I don't care too much about my appearance, so the only difference to me is that I have to buy a few more jumpers, as I'm wearing them 7 days per week, and not just at weekends. However I know half of the girls now wish we had school uniform, thinking "oh no, what will I wear?" and spending a lot of time chosing what to wear each day... you know how girls are. I suppose I'm slightly on the "no school uniform" side, but don't feel especially strongly either way.

It's not the fact that lots of electrons make it unstable, it is that having specifically 60 electrons is not stable. 50 or 98 electrons would be. I've heard of a molecule being held within another molecule, that would be called host-guest chemistry, I think. I suppose if a molecule was inside a fullerene it would be trapped, but how would it get there in the first place? Also I think that adding another molecule inside the fullerene would change the electron configuration. You can't have the electrons deep inside the fullerene if there's a big molecule there. And if the outside of this inner-molecule was negative, like CCl4, then the fullere's electrons would be repelled from the inside. I'm not saying they would go outside, I don't know, but it would have an effect.

ajb, the LaTeX isn't working, if you can get it to work I'd be interested to see what it was. Severian: I know this was from two months ago (to the day, as it happens) but I can assure you differentiation is in the syllabus. It is in C1, or Core 1, the first thing you get taught in year 12. Found here: http://en.wikibooks.org/wiki/A-level_Mathematics/C1/Differentiation You then get more in year 13, found here: http://en.wikibooks.org/wiki/A-level_Mathematics/C3/Differentiation and a little bit more in year 13: http://en.wikibooks.org/wiki/A-level_Mathematics/C4/Advanced_Differentiation As well as plenty of integration to top it all off. And that's all for just maths, if you're doing further you get loads more. Klay/CPL: I know what you mean. It's not that hard, you just notice your original integral appearing in your answer... Erm, what kind of trig? We start learning what trig functions are, the real basics, at the age of 15 or 16. At that age you're expect to use it to calculate lengths and angles. Then that's developed all the way through your education. I suppose there's all sorts of differentiation, equalities, integration and introduction to new functions (arcsin, arccos, arctan, sec, cosec, cot) at the age of 17 and 18. Although if you take further maths you go further (no pun!) still with advancing all previously mentioned areas and more trig functions (cosh etc.).

Oh, my bad, me neither!

AFAIK the electrons are most likely to be found in the center of the fullerene, ie. within the ball structure. You know the electron's position is given by a probability field, so I would have as a guess that the regions inside the fullerene and very close to the outside would be where the probability field is highest - that is, where the electrons are most likely to be found. Hmm, interestingly enough if you check out the QM part of the fullerene entry on wiki: http://en.wikipedia.org/wiki/Fullerene#Quantum_mechanics then it says that the electrons do not delocalise over the whole Buckminsterfullerene molecule. This is to do with whether the electrons can delocalise over the whole molecule whilst remaining in a stable state. 60 electrons cannot do this. It says that in water it tends to pick up two more electrons and become an anion. It also suggests that bucky balls might try to form a metallic bond between each other. Which doesn't really answer the question... maybe someone else can help us.

I was having a discussion earlier and wondered when a baby's first heart beat is. I think it would be at some point whilst the baby is still in the womb. But then what sets off this first beat? Is it some kind of electrical impulse, from where? Or a signal from the baby's own brain? When does a baby heart beat for the first time and what initiates or stimulates this first beat to occur?

So if a block moves upwards at 5m/s then upwards is positive. So acceleration due to gravity would be -10 (note the negative) (often a more accurate 9.81 is used), because gravity acts downwards, and you've just define up as positive, therefore down is negative. Of course you could work the other way round too. You could say that the block moves upwards at -5m/s and therefore acceleration due to gravity would be 10. It doesn't make a difference as long as you keep the signs the same throught the question.

True. But like mobile phones and wireless routers they are not that powerfull. Whereas this application would require an EM wave which sends enough energy to power computers, lights and all household equipment. Sending signals do not require that much power, a mobile phone is safe to use, but can you imagine an EM wave which supplied 3kW for your electric heater just freely stretching between some power supply in the street to some power receiver on your house? I still don't like the idea. What happened to the fact that standing waves do not transfer energy? And to get a standing wave you need to have the same frequency waves in both directions, for that you're going to need to get your receiver to produce waves as well, which requires power.

What! Do you play chess? How can you not have heard of draw by stalemate!? Imagine your opponent only has a king, and you corner it such that it is not in check, but if it moved it would be, then the king cannot move, therefore your opponent cannot move, so it's declared a draw. Stalemate is where your opponent cannot move, the real life situation of that is that your opponent cannot move without putting themselves in check, which they're not allowed to do. OK, so the solution... I used to do this a bit, it really gets quite annoying doesn't it! The only advice I can really give is to stop and think. I can, when it comes to the end game, think a few moves ahead, which can really help. However when I was in my 'stalemate' phase I couldn't think so far ahead (this was a while ago, when I was younger). If you can't think many moves ahead then my best advice would be just to think of your opponents very next move. Think to yourself "if I move to that square (and I find it helps to picture it) then what can my opponent do?". If they only have one king they can only move into one of 8 spaces (or fewer). In your head take your move and then imagine you are your opponent and see what they can do. I used to say "he could go there" or "he can't go there" (ie. it would put him in check). If he can't go anywhere and he's in check then you win. Just one other thing would be that sometimes I would be in a situation where I would actually have to make a defensive move just to avoid stalemate. I would totally screw up my position and the game would take an extra 5 minutes, but you have to if you want to win.

Thanks for the link. I spent the last hour watching "Physics 10 - Lecture 18 - Quantum II", which was quite interesting. Whilst I knew a lot of it, he threw in little extras which I found very interesting. So he introduced energy gaps, levels & bands, at a simplistic level, but he then went on to show why other bands were not possible. It's related to when the electron wave catches up with itself and the waves are out of phase and cancel out. As the electron cannot, in real life, cancel itself out you can conclude that such an orbit or energy level cannot exist. Another example would be that an electron in a superconductor is in the ground state, obvious. The interesting expansion was that if an electron collided with something then it would not gain enough energy to enter the next highest energy level, therefore it cannot collide in the first place. Whilst I didn't think it was the most inspiring lecture, nor did it have the "x-factor", it was thought provoking and quite interesting. I hope to watch another one of those as soon as I have the time. Thanks again.

Thanks for the diagram. Best way to do this is to use Windows XP. Go to Control Panel > Network Connections and on the left under Network Tasks and select Set up a home or small office network. Once the network wizard has been run on both computers they should be able to see each other's Shared Documents. Complications: firewalls will need to be correctly configured. You will also need the correct protocols installed. Go to Network Connections and right click on Local Area Connection and select Properties. If, under the General tab, something called File and Printer Sharing (or a similar name) is not there then you will need to instal, select Instal, it is a Service and then just follow the wizard. To share the printer go to the Control Panel and select Printers and Faxes. Click on your printer and on the left under Printer Tasks select Share this Printer. Try that lot and see how it goes.

There are, sadly, hundred of websites like this, and they're basically all wrong. If something this big was true then you would read and hear about it all over the media. And at that point it's worth investigating, because whilst the media seems to have little scientific knowledge, they can at least filter most of the rubbish that's around us. I'm not saying use the media as you're income of scientific news; I'm just saying that any major breakthroughs would be reported in the media.

Well [math]F = \mu R [/math] is an approximation of the frictional forces on a static body. When a body begins to move [math]\mu[/math] changes value (usually a decrease) to [math]\mu_k [/math] (coefficient of kinetic friction). So [math]\mu[/math] changes. We know that [math]F = \mu R [/math] is only approximation. We also know that the frictional force on a moving body varies with its velocity. So I would have as a guess that when the velocity is significantly changing a different, more accurate, formula is required.

I saw that too, I'm skeptical. A prototype hasn't even been built yet, let alone tried to be used for real life applications. Apparently it works in theory, maybe it'll work in practice, unlikely it will become widely used. Or that's my view, at the moment. Ideas like wireless energy have been around for a long time, intelligent people like Tesla did a lot of work on it, but at the end of the day we're still using cables and plugs. Maybe it will all change one day, but I seem to be automatically skeptical of things like this. I was skeptical of the relativity drive or electromagnetic drive (emdrive) when I first read about it in the newspapers (and then more scientific sources) a month or two ago, it was "the end of wings and wheels" (quote: Shawyer, the man who developed it). Thats now been widely rejected. I was also skeptical when I read Tajmar's claim that gravitomagnetism is a lot stronger than Einstein predicted, that's now widely viewed as an experimental error. I haven't seen much on that BBC article, but I remain skeptical - for a change!