studiot

Yes it is an old post and you should have started your own thread for an unrelated question. So don't be suprised if a Moderator splits this off. Since you are studying a biological science subject you should have posted there for a biologist to reply. I think you are making too much of the whole issue and confusing yourself. A hundred years ago or so scientists drinking brandy in their fashionable clubs realised that most, if not all, the quantities used in science could be built up from a few basic ones. There are many possible selections of basic quantities to choose from so they had more brandy. After a few more brandies they established the beginnings of the current system as the most convenient. This is the one you are using today. Those combinations of special importance or interest have received special names in their own right, for example energy. Some combinations are, to put it frankly, not important enough to warrant their own name In that system the metre is represented by a small m. A large M is used for Moles - a chemistry term. Unfortunately there are more quantities than letters, even with the greek and other alphabets included. So m also represents the prefix 'milli'. So I would guess the units of glycemic response to be milliMole -seconds edit milliMole -minutes

I am sorry I rather scrambled my last post so you missed the main point which was that you don't only have to consider the lance length you must also consider the shrinking empty space between the jousters.

You are correct the answer to the OP probably has to do with the temperature of the water. Asthfx perhaps you live in a part of spain where they don't have ice? If the same mass is squashed into a smaller volume will the density go up or down? I have underlined you proposed answer. Chapin if you define % change you will see that a positive tells you the density has increased, but a negative change tells you that it has .................? Do you know that water is an anomalous substance? For most substances density increases as temperature falls and this is true of water between 100oC and 4oC but water has its maximum density at 4oC and the density then decreases between 4oC and0oC. When water freezes it expands so ice floats on water, unlike most solids on their respective liquids.

I have started a new discussion about wave/ particle duality in the quantum theory section http://www.scienceforums.net/topic/110124-wave-particle-duality-inspired-by-a-thread-in-chemistry/ I will address the (useful) remarks by BanterinBoson in a second reply.

Discussion of quantum theory is getting in the way of discussion about chemical spectroscopy in this thread and we all agreed that it would be better conducted in a separate place. As this forum has an allocated palce for quantum theory I am starting this thread to promote that discussion. http://www.scienceforums.net/topic/109814-vibrational-frequency-co2-global-warming/?page=2&tab=comments#comment-1014291 Here is a kick off post by BBoson by way of explanation. Let's save that for other discussions I agree that quantum mechanics is quite different from classical mechanics. Like classical mechanics, QM can be approached at different levels from different viewpoints. One such is using 'wave packets' to describe duality A classical wave extends to infinity in both directions. Mathematicall the classical wave equation has no beginning or end. We simply ignore that part of the mathematical equation outside our region of interest. A wave packet has a beginning and an end and can be used as a model as to how you can have wave/particle duality.

I think the key to this one is to realise that not only does the each jouster see the approaching lance as shorter than his own but he also sees the distance between himself and the tip of the moving lance to be shorter. That is he sees all distances in the moving frame (considering himself static) shorter along the inter-line.

I hadn't noticed the commutator one so thanks for pointing that out. I was was thinking more of the Driac bra & ket notation and also the repeated sub/superscript notation, and any othere extreme shorthand notation I may (probably) have missed.

This is a good one for the long winter evenings ahead. But please indicate for the sake of those of us who don't do this all the time, the meaning of your bracket symbols.

The answer should be that I have given you some new terms for you to look into. There is a more modern explanation in particle physics, without forces at all, that Swansont and Sensei are offering, but this is a good route there, following the historical development of the subject.

There is more to it that that. Is an aerobic microorganism more complex than an anaerobic one, or just different? The original lifeforms were all anaerobic since there was no oxygen to start with. In fact oxygen was a poison to them, to be excreted by them.

Here is a simpler summary of one of our models that best moves on from what you already seem to know. Yes potential energy is stored in the arrangement of atoms within a molecule. This energy is electrostatic in nature as is the force that generates it. You are right in observing that this force opposes the cramming together of like charges as we find in the nucleus. So there must be other forces involved and your question seems to be about what these are. Furthermore these forces must be stronger than the electrostatic ones. We identify four what are called fundamental forces. 1)Gravity 2)The electromagentic force 3)The strong nuclear force 4) The weak nuclear force All four lead to a potential which can be regarded as an energy store. Early physicists discovered that the strengths of forces (1) and (2) vary with distance, the stength falling away as distance increases. They also found that the electromagnetic force is many orders of magnitude greater than the gravitational one. When physicists asked the very questions you are now asking they realised that the forces holding the nucleus together must be very short range compared to the first two. So these forces really only act within the atom. So just like the arrangement of atoms in a molecule, the arrangement of sub atomic particles in an atom can be regarded as storing energy in the potential fields of (3) and (4). As already noted the internal electrostatic field within the atomis small by comaprison . This energy is known as binding energy. Now observation has shown that the binding energy per nucleon varies with each atom. This is shown by what is known as the packing fraction curve. And this is interesting because this curve has a minimum at atomic number 56 (iron). This means that if nuclei smaller than iron are combined energy could be released until the resulting combined nucleus is that of iron. We call this fusion. Equally nuclei larger than iron can release energy by breaking apart to move towards nuclei of the size of iron. We call this fission. As you say there is a thermodynamic imperative for this, but it is due to energy not entropy. As with all thermodynamic calculations we work this out by adding up the sum of all the potentials of all the species before the process and comparing that with a similar sum for the species after. This is how fission can release much smaller particles than iron as well. There is a net energy release. As a matter of interest, I think but I am not sure, that our Sun is not hot enough for even helium to fuse, that happens in a nova. And to get all the way from hydrogen to iron to need a supernova.

If you want to become an expert on Newtons Laws I would recommend you follow the standard notation. Otherwise I) You will fail exams when they ask you to use N2 to prove something and you use the wrong law. 2) You will stumble over communications with others as you have just done with me. 3) You will come across more difficulties when you start to discuss the application to circular motion. Now would you like an answer to your question about Netwon's second Law, N2?

Let us start with a correction because you have stated Newton's second law not his third. So did you mean really mean N2 not N3 as they are called for short?

Flat does not refer to thickness (nor length nor breadth, nor width.) It refers to the way distance is measured between one point and nearby points.

Several members have told you useful things that anyone genuinely interested in Physics would wish to know or, if they did already know, then simply say a friendly 'yes I have come across that' or wording to that effect. You either ignore these things that are said to you in good faith or argue with them. Is that a good strategy?

You have already been told that 'u' is not a word in any English dictionary.

That is exactly what I did say. From what I can see you do understand reasonably good English, you just aren't prepared to use it. Don't you think that is rude to other members here?

Since you can't seem to read either your own writing or mine let me try again I have underlined the part of my post where I told you just exactly where that incomplete bro lies.

No, it is you who is wrong. The photon does not have dual nature. The photon is a particle. But light has dual nature since aspects of the behaviour of light are consistent with wave theory and with not particulate theory. By the same token, some aspects of light are only consistent with particulate theory. And we call those particles that observe this behaviour, photons. I am disappointed that when I pointed out the only maths equation you have quoted so far (in your opening post) is incomplete and you are completely silent on that subject.

Good research silvestru. +1 Too many people argue against Einstein, 'quoting' what he did not say. ovi issac You seem to think that the popular phrase energy and mass (or matter) are equivalent mean they can be interchanged at will. That is not the case. In fact the popular equation E = mc2 is only part of the full relativistic equation. Have you studied the maths of relativity?

It is up to you to make yourself clear.

Well you seem to be mixing up mass and energy in any old way. Relativistic mass is not the same sort of property as ordinary mass. And I still don't see a question if , as you say, your question is not Where does the energy come from?

Please rephrase this, it is quite garbled English.

Is this your actual question that you would like answered? Think about the answer to this question. I throw a ball into the air. Where does the energy for the ball to acend come from? The answer is the same as the answer to your question. From whatever causes the motion. In the case of a photon it starts off life with a fixed energy and can never change this.

Schools in England (Scottish, Irish schools start a little earlier) have just restarted so this child will be in her first couple of weeks of secondary school. And yes an 11 year old could easily have started this year, that's nothing new. I started at 11, it depends upon your birthmonth. However in my day we only did 'general science' in the first one or two years (can't remember which now) and very little practical at that. There was not enough time on the timetable to separate the sciences. I had a choice of German or Chemistry when the reduction towards GCE came. But I return to the point about supervision. This child has had now many Chemistry lessons? A couple, three at most. And she was asked to pour out a chemical that is listed as a potential hazard to health in the safety regs. As I recall glass rods were taught for this process and a swift surf shows this is still the case. Had this been done in this case? A word for John, My apologies I'm still trying to get the hang of the new quote system here - it fights back and doesn't always behave as one might like or expect - and something obviously went badly wrong as the wrong quote was included in my reply to you. No wonder you were a bit confused about it.