studiot

Remember this is your title to the thread, not mine. I don't see any carbon in this. So what burns? Hint I could set light to it with a match and it used to be a component of town or producer gas, before the days of natural gas. http://en.wikipedia.org/wiki/Producer_gas

The answers to all your questions were in my post #7. Multiplying through by 100 was just meant to make life easy for you. So after a good laugh at your joke, what burns?

So what happened to my post#7? Did I waste my time?

The question also told you that But you have made no attempt to use this information. So I'm quite sure that either your lecturers or your tutor gave you much more information than you seem willing to let on. Yes the equation you quote (from your lecturer) is appropriate, but only when you understand what you are doing and we have some way to go to reach that stage. So just please try to answer my simple questions and swansont's and don't offer any additional information. This trail will eventually lead to the answer you need.

Does it? I thought it stated that the change in internal energy = the sum of the work done and the heat exchanged dU = q + w or dU = q - w, depending upon your sign convention. Can we discuss the problem in these terms since that is what your lecturers are expecting?

Here is a hint. This question is about the first law of thermodynamics. Can you at least state what that is so we can take it further?

Since when did they start measuring volume in kilograms? Why can you not simply answer the questions swansont and I asked? They are very simple and very basic and will lead you to the correct answers.

You joined at 1804 today and you had posted 19 homework questions by 1814, when you left. Is this a record at one every 30 seconds? The price is £1,000,000 payable in advance.

So start by following swansont's advice. Actually this is good advice for all physics questions (He was a physics teacher after all) List what you know. Then list a few things you don't know, but might like to. So What is a closed system, why did they specify one? If the question also specifies work can pass the boundary, what else can and can't? What formulae do you know connecting these things? I am going to cut the grass now, but I will look in for a cup of tea and to see how you are getting on, from time to time.

If you can do the 'calculations', why do you 'need the formulae' ? Which formulae? As I see it, this question is testing your understanding, not your arithmetic so explain what is happening.

Who said it was undefined? It may be that it is not calculable. That would be the case with your example since we don't know what a and b are and their relationship. 'Some number' is correct, but that number is not fixed since there are many different infinities and 'some number' will be different depending upon the circumstances.

+1 each for good communications. I strongly suggest you don't use fractions or decimals in chemical equations (for balancing). Multiply through by 100 first. Each coefficient ie supposed to stand for one molecule (or 1 gram mole or 1 kgmole). As to pavel's second helpful question. You have (correctly) called this a combustion process. Combustion is combining with oxygen (oxidation). So what burns?

Just to take up this point a little further. We discussed in your other threads that things in general and infinity in particular have 'properties'. Properties are the means by which things interact with other things. They are the means by which we can observe and perhaps measure this interaction. Observing one particular property does not in general say anthing about another and different property. With particular regard to infinity. One property is that it can be considered in some sense 'going on forever'. This property is what we talk about when we take limits and think of the relationship between infinity and ordinary numbers. The idea that if N is an integer, there is always an integer (N+1) bigger than N and you can go on adding N forever. That is you never get to the end of the process. But this is an inconvenient property and for some purposes we consider the entire sequence is finished and present. We do this for projective geometry - the point or line at infinity is always there, not somethign we can never reach. We do this for the different properties that ajb mentioned on the extended number line. We do this for a whole theory of different infinities or different properties of infinity. These properties are not necessarily transferable so don't mix them up.

Careful. We are applying some rules of some of mathematics. If what you said in post 21 was completely valid then what about an alternative rearrangement of the equation, such as I offered in post#5, that does not lead to a contradiction ? This view, of course, leads to an alternative view of infinity.

In English maybe, but not in mathematics. Look up countable (denumerable is a posh word) and countably infinite.

So, as John said, the OP was not an idle question. One further point is that what we are prepared to accept x to be is very important. We have all agreed it cannot be a Real number. The null set has been proposed as a 'solution' to the equation. So what do we mean by and equation between sets? Infinity has also been offered and , Fool, you have noted elsewhere that one definition of infinity is "An infinite set is a set that is equivalent to a proper subset of itself.", although you have not come back to that thread for some reason? Of course the null set is a set with no proper subsets - a sort of 'opposite end of the spectrum' to the infinite set. One a further note, the issue of the difference between zero and nothing has emerged for discussion about every four to six months since I have been here. The site search is very poor in this respect but there are several threads discussing this at great length. One consequence of the null set is the observation that it is possible to build all the numbers from nothing at all. Start with the null set.= {} = 0 Construct a set with one member only, the null set ={{}} = 1 Construct another set with two members, the null set plus one copy of the null set {{},{}} = 2 and so on.

Apologies I see your post in lucky number13 now It was so long I missed it. Thank you fiveworlds.

I'm sorry I don't see you having mentioned its composition before. However, enameled steel is safe with hydroxide, so as you take safety precautions about yourself. Oven spray is the most convenient, likely you will need several applications. I would warm the pan with some hot water first. Discard the water, take the pan outside and spray on. You will need to leave for at least half an hour. Then sluice off the excess with water. Then scrub off as much as you can with one of those non-scratch sponge and plastics scourers. Repeat several times until as clean as you want.

So there is more than one solution to the equation. So what, that is not an uncommon situation. In fact some equations have infinitely many solutions.

There are also potential building control issues. Electrical rules in the US are stronger than in the UK. In particular the standard domestic supply for A/C, heating and other large power users is to use 240 volts. The 120 is only half of the split phase system and designed for lower power/duration equipment. In the US the neutral is the centre of the split phase system and must be grounded. It is ironic that in the UK it is illegal for the consumer to ground the neutral, in the US is is illegal for him not to.

The only real issue with infinity is that it obeys different rules from real numbers. Therefore you require different mathematics to handle it Folks get into difficulty because they keep trying to make it follw the normal rules of number and then find inconsistencies when it doesn't. Use the appropriate maths and all will be fine. Note this is not to say we know everything about it. That would be crass arrogance.

That is a poor train of reasoning. The OP believes (wrongly) that there is no solution as evinced by the words "I understand that there is no solution." The OP then allows for the possibility that he may be mistaken by asking the question Are you asserting that infinity is not a correct answer to the question "what still equals itself after one is added?"

+1, acme. Don't fiddle with the mains unless you can be certain you know what you are doing, including the possibility of invalidating any household insurance you have.

If it looks like a duck and walks like a duck and quacks like a duck.................................... The definitions you posted in post1 are definitions by property. That is properties of the defined object are identified. The trouble with that sort of definition is that you can never be certain if your list is complete. However the more properties you can identify the more confidence you can have in your definition, as with the duck. Further in both post1 and with your riddle is only one property is identified. Negative properties ie "X is not ..." are really useless in definitions, although they can offer some intuitive feel. In your riddle list there is on one item written in decimal digits so, from that point of view it is the odd one out. As "is not..." might be that there are two words with eight letters so neither can be candidates from the property of number of letters.

Well the key to understanding either definition is to understand what is meant by 'equivalent'. Stating "set A is equivalent to set B means that you can put each and every element of set A in one-to-one correspondence with an element of set B, with no elements 'left over' in either set A or set B. So definition 1 says that the elements of every finite set can be put into one to one correspondence with the set of intergers {1,2,3,4,.....n}, but that an infinite set is a set for which you cannot do this. Definition 2 says that you can chop out a chunk of an infinite set (posh words = proper subset) and put its members in one to one correspondence with the whole set, which is not possible for a finite set. For instance you can put every real number between -1 and +1 into one to one correspondence with every real number. Does this help?