http://en.wikipedia.org/wiki/Dimensional_analysis
This may also be helpful, Marc.
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http://en.wikipedia.org/wiki/Dimensional_analysis
This may also be helpful, Marc.
Exactly as I saw the equation.
I think that there is some confusion in how the question was written.Quote:
Frank said 1/2/1/2 = 1/2/2 = 0.25
But 1 half divided by 1 half is 1.
1/2/1/2 is the same as 1/2 divided by 1/2 = 1 because 1/2 goes into 1/2 just once and precisely just once.
Frank no doubt took one look at this and thought "Gawd - what was I thinking".
If it was written (1/2)/(1/2) then I would have looked at it differently. There are obviously limitations to the way formula's can be written in the forum
If we were to say it is permissible to call the question ambiguous then we would have to give all possible answers as for something to be ambiguous there has to be two or more possible answers - not just one - if only one answer is given then the question was not perceived as ambiguous but was merely misunderstood.
If the question has more than one possible answer then they might include those derived from interpretations such as...
1/(2/(1/2)) = 0.25
1/((2/1)/2) = 1
But to say that 1/2/1/2 just means 1 divide 2 then divide 1 then divide 2 is to treat 1/2/1/2 as an instruction sequence rather than a fraction. If it is to be treated as a fraction then is has to be broken down into numerators and denominators.
Now, can we have a fraction such as 1/2/2?
No we cannot. A fraction must clearly demarcate numerator from denominator.
The convention, in the absence of brackets, is to start at the top identifying numerator then denominator then numerator then denominator.
Can only say .......... I agree with this :cool:
Isn't that the whole reason for having standards and agreed formats to try to reduce missinterpretation. Hence m/s/s is written m/s2, and so on.
Any doubt with 1/2/1/2 would have been to look at it as 0.5 / 0.5 "simple" ;)
Seems like you are going back to your old ways my friend.
Do you ever admit to being wrong, or in fact admit to possibly making an error?
There must be a psycological term for someone that is never wrong..........
Count me out of any further responses.
Indeed
m/s/s when treated with the conventions universally applied to fractions in the western world (perhaps everywhere else too) is interpreted as m/s/s/1 which was the whole reason for me starting the thread because I come across so many people who do not understand this and at the same time I believe this to be one of the key reasons people struggle to make full use fo the tools of physics.
If m/s/s was not implicitly m/s/s/1 then we just could not get to m/s²
m/s/s/1 is the same as m/s x 1/s = m/s²
And if you accept that then you have to accept also that 1/2/1/2 = 1 otherwise you are flat out contradicting yourself.
Are you taking about me Frank?
Firstly - I have never changed my ways and never will - my ways and me are the same thing - they are inseparable.
When I know I am wrong I out loud announce that I am wrong. But right now I believe I am right about this - I could be wrong - that seems to me to be possible - that is why I started the thread - to weigh up a balance of arguments for and against. But so far I believe the arguments for are very much stronger than the arguments against and so this far I genuinely believe your arguments (not you) to be wrong and my arguments (not me) to be right.
Someone who is never wrong is a genius of extraordinary levels. But if you read David Hume's works you would understand that we can only ever learn from making mistakes. If I know a good amount of stuff then it is because I have more experience than others at being wrong about the same stuff at some stage.
Since you can only learn from being wrong and making mistakes - because being right is probabilistic and never a certainty - I put these questions up so that I and others can become more right out of experiencing more often more mistakes. If you are not willing to make mistakes then you are also not willing to learn.
Do you honestly believe - without doubt - that your answer is the correct one?
Do you know what the definition of arragance is?
(.)(.)
I think i've found my level :D
Frank - use this online calculator to calculate 1/2/1/2
http://www.calculatorsoup.com/calcul.../fractions.php
^ lol... :)
Tits or tyres, nothing but trouble :p
Question
If I'm stood underneath two condensing units, one weighing 100kg and one weighing 75kg, each vertically mounted side by side with a space gap of 300mm, at a height of 100 meters, air temperature @ 20 deg C, RH 68.6%, wind speed @ 11.7 mph/19.78 kph. And both units detach themselves equally at the same time due to poor fixings, fall and land on me.
Which unit will hurt me the most? :p
Chilli, neither as you would be dead, but.. thats just an opinion. Cartoons come to mind,whistle.... followed by splat and a cloud of dust. Coyote lives to recalculate why both condensing units fell at different speeds.
So Frank - do you not feel compelled to admit error yet?
Does "Count me out of any further responses" mean "Oh **** - if I hang around here I'm going to have to sooner or later admit I was wrong"?
You know, the difference between an arrogant antagonist and a sincere one is that the arrogant one will merely rebut your claims without explanation whereas a sincere one will at least try offer argument and evidence.
Of course it is possible you genuinely think you are right? I think that would be very odd - it would very much surprise me - but it could still just be that you genuinely believe you are right - in which case you are not obliged to admit you are wrong - it is sheer nonsense to ask someone to admit they are wrong when they feel sure that they are correct.
I do think it comes down to how it is written, if I remember rightly, if you were calculating a fraction, the fraction was in a small font, with the comand in a larger font 1/2/1/2
The answer would then be clearly 1
I have read this thread from start,,,and i find watching paint dry far more interesting.I reckon coolrunnings post was spot on,yes go back and have another look at it and i think everyone will agree,,but unfortunately some people are too thick to absorb anything other than their own opinion.
Yes, the whole point is to establish a certainty of understanding with regards to the units analysis when considering say specific heat capacity kJ/kg.k or acceleration m/s² because no matter how much anyone does not like it these truly are just peculiar cases of complex fractions as in 1/2/1/2
That makes it kJ/kg/K/1 and m/s/s/1
I see no available argument to support any implied claim that a school child being introduced to fractions and ratios will be taught that 1/2/1/2 means 1 divide 2 then divide 1 and then finally divide 2. I think this is sheer nonsense. More likely the result of 30 years absence from studies than any erudition :)
I wholly reject the proposal that 1/2/1/2 is not a fraction having no numerator or denominator but is instead merely an instruction sequence.
There is no evidence available to me in any of my math books or any where on the web.
Therefore the matter is not ambiguous - there are not two or more different ways to interpret the arrangement 1/2/1/2. It can only be (1/2)/(1/2) and any other interpretation is a mistake.
go to excell and type
=1/2/1/2
what is the answer?
Type as you have written, no f***ing with fuctions, or brackets.
whats the answer?
It can only be (1/2)/(1/2)
CORRECT
That is your mistake Mad Fridgie :)
The convention with complex fractions taught to school kids and used in physics is that 1/2/1/2 must be read as (1/2)/(1/2) and not any other way.
A computer sees the number and function string as an instruction and so for you to get the right answer using excel you have to inform excel of the convention it is supposed to use and so with you string of instructions you also have to include convention instructions.
My question is not "What would excel do?" but rather "what is the convention?".
Lol, do you have an honest reason for believing so or are you just in a happy clappy keep the peace lets all just agree to agree and smile type mood? :)
I'm after the truth here - I don't give a **** about how unhappy or happy it makes anyone - only the truth please :)
You Quoted
"There is no evidence available to me in any of my math books or any where on the web."
Well excell is one of the most commonly used pieces of software, so by nature is convention.
Flynn verses the state, are porno mags convention, he proved it was due to how much porno films were watched.
I also clarified that Bodmas was used or that fractions were written in different fonts, to distinguish between fractions and string instructions.
What was the answer on excell, you never answered the question?
I work with excel all the time - I produce little windows applications in Pascal - I do not have to do it in excel to know what excel will do.
You could say that because I am aware of what excel will do I am aware that it is not immediately obvious to everyone that 1/2/2 is the same as 1/2² and hense the thread. It has the answer but the method to go from one to the other contradicts the method excel follows.
Consider again what Frank says: 1/2/1/2 = 1/2/2 = 0.25
How on earth does Frank establish that 1/2/1/2 is the same as 1/2/2?
In other words how does Frank turn a 1/2 into a 2?
Why did he turn only the bottom 1/2 into a 2 and not also the top half. If he also turned the top half into a 2 then he would have 2/2 = 1.
Also then, why did he not instead just turn the top half into a 2 which would have given 2/1/2 = 4 or by your standards = 1
I think you guys are just trolling - seriously - I can't believe this nonsense.
what is happy or unhappy to do with it, the truth is you get self satisfaction by attemting to belittle others. Your are obviouly lacking self cofidence, even though betray confidence. I bet you look in the mirror every night and tell yourself what a great dude you are, but deep down you see yourself as just a little kid, doing what he needs to do to get attention.
You are just a bully, who likes to throw his intellectual weight around (no doubt you have excellent knowledge) Why do you not use it for the common good, then people will give genuine respect, it will make you feel good, unless you are happy being a miserable barsteward.
I'm only interested in the matter at hand - as you will notice - I never belittle or attack anyone unless I their focus slips from the subject at hand to some irrelevant personal matter.
I never commit the ad hominem fallacy - I never do this - I never get personal - I always stick to the subject. But as soon as someone's insecurity or lack of skepticism causes them to get personal I will put them in their place - I will remind them that they must stay focused on the matter at hand.
If you go back through all my discussions you will see that I stay true to the technical ebb and flow of the discussion.
You will remember that, for instance, it was Nevgee's insecurity that brought him to complain that my discussions on the Iraqi guys AHU were off topic and there were a few other irrelevant person comments he made - but in the end - I was right - I had been steering the discussion in the right direction from the outset and anyone following would have learned from me - learned a lot and for free :)
Did you not quote there was no evidence?
simple answer "yes or no"
I proved there was. so you are wrong, accept the truth
I asked you undertake the equation, which you did not. So what is the answer, do it?
Then you can accept that yours is not the only method of achieving a result.
If you believe what you have written, then to you it must be the truth, and for that I can not argue,
Do you not understand, that we do want to learn from you! but believe me that you come across as some one who belittles most, maybe your intention or not. Have you ever been in love? does not make any sense.
Here's a quote:
I implicitly agreed that excel will follow the numbers and functions as an instruction sequence. But I also explained why - if I were to follow yours and Franks example I would now also get personal and ask you what is it that your personality is lacking or what particularly is the deficiency in your emotional intelligence that causes you to deny the abvious - the obvious being that I replied to your comments on excel and gave my opinion that that was your mistake because excel needs all of the instructions of the conventions. But I do not get personal - I do not start to question what insecurities you might have that causes you to miss that argument I put and its implicit message that I know what excel does with the "equation".
Maybe you are not trolling - I just feel you are.
What Iam indicating that all information should be shown with common clarity, one can not presume that all, already know your particular methods and descriptions.(and if they do not does not make them stupid or lacking in intelligence)
There is a simple saying
"presumbtion is the mother of all F***Ups.
I am sure if you had written the calc either in brackets or in different colours all would of come up with the same answer. Your argument is nothing to do with maths, but more to do with interpretation of data.
Honestly - this is irrelevant to the topic at hand - utterly irrelevant to the matter of how truly does m/s/s become m/s²
You should never get personal in your discussions on the web unless you have something nice to say. Getting personal on the web has to be asymmetrical - it has to only be nice or supporting etc and not criticising or attacking. otherwise - as you see - you will get someone like me who is technically superior to most - by my own making - thanks to no one but myself - and you will get put in your place.
Now, if you don't mind, I really am interested to find a crack argument to establish the truth here.
I have already said so to Frank that I am willing to consider the chance that I am wrong - and I even explained that that is why I want to discuss the matter because I have my doubts. But all the evidence I find on the web and in books says your argument is nonsense - it just cannot be.
You might still be right - there could be something you say to clinch my understanding that could swing my beliefs about the matter but by the only conventions available to me 1/2/1/2 has to be 1/2 x 2/1 = 1 and so I have no choice yet but to see your arguments as nonsense.
Mad Fridgie has the more sound grasp on convention here that I can see.
I see the problem as 1 divided by 2 divided by etc unless there is a clear emphasis put on the "central" per (as MF mentions). That in itself if agreed by the majority of the participants on this forum, is a convention, until tried against a more popular convention that is.
It's only a presumption or assumption if you actually presume or actually assume. But if you tell people what your assumptions are then they are no longer assumptions but matters brought out into the open overtly for consideration to be tested as to whether they can be assumed good.
Generally something is considered an assumption because the person did not realise it should be mentioned - it does not help to tell people they must not forget to tell certain things they see obvious because if they never did then there would never be assumptions.
If I am assuming anything then by definition I may or may not realise what I am assuming and if I do not realise something it does not help to tell me that I should realise it - maybe I also don't realise what it is I should realise I should realise.
Can you think of a reason why in physics I should drop the convention that 1/2/1/2 is 1/2 x 2/1
Is it possible that I am mistaken in seeing m/s/s as also m/s/s/1 to be treated as m/s x 1/s ??
Can you see you have changed without know it, how you written each calculation
Option 1
1/2/1/2
1/2X2/1
option 2
1/2 / 1/2
1/2 X 2/1
can you see the confussion
option2 calc one is very clear (but not the way you have written it), option two is how you have written calc two.
This where confussion lies, need for clarity