Challenge Questions

GA

Well, this is going to be a short thread - maybe we should calculate how long it will take to fall off the table too.

GA - Darn! By the time I see the challenge, most times it is analyzed and solved. 15 minutes was my response (seemed pretty simple) but sometimes there is a more creative interpretation or solution.

I was surprised when I found the puzzle, it had been up for about a day with no answer yet. I am happy about it, it brought me my first GA. Thank you all for that.

You are welcome. GAs are strange. I had first 3 as a guest and none since registering. I have seen many that look like they are the best expected, but because I could not validate it, I had to allow others better qualified to give the GA. I personally find the value of CR4 to first be valuable shared information and experiences, second to helping others and third the recognition (some times a thank you is better than a GA).

If it looks to be a thoughtful, relevant and insightful answer to you, I think you should put modesty aside and give it a GA*. If subsequent contributions show it merely to be misleading, then you can always change your mind.

I'm aware that there is a problem with the standard way of changing your mind, in that you can only change between GA and "off-topic", when all you wish to do is cancel your GA. My solution is to give an off-topic vote under another identity (I know, alternate identities can be used for less ethical reasons - but let's not go there).

*There will be plenty of less-informed people giving ratings, so it won't be harmful.

Your proposal makes sense, but I still feel obligated to reasonably judge myself qualified before giving a GA. I have found it frustrating going through a good thread, where I have limited knowledge, trying to weed out the not so GA and want to avoid contributing to that situation.

Thanks for the guidance.

The problem being that you can't see who gave the GAs, so they only aid judgement if the majority of those voting are better-informed than you. Currently, the most that we can say for GAs is that they can be a guide as to which answers may be worth reading (and not always good guides at that)

Having seen your postings, my belief is that you value insight - and such is worth reading even if not entirely correct or complete.

For myself, I tend to add a comment as well as a GA if I think I know what I'm writing about and there's any disagreement.

Thanks,

I respect your opinion and value your judgement!

90 mins

Needs to cut & weld 30 links (17+13) to 60 links.

Hi slideruler,

I have enjoyed the chain based challenges immensely (as a witness).

Might I suggest you sharpen up one or two things.

Firstly please use preferred metric increments.

cm is for dress makers and hat makers, though I acknowledge/understand the dyne made easy intent.

mm or m is 'preferred' - ie 1000 multipliers

Second; everyone assumed in "pendant" that 1 cm 'long' x 100 links = 1m total length.

or they read "length" = "effective pitch" = 1cm (so 10 mm) = not necessarily 1 m - is it?

aka "assume" = all wrong - even without the ? angular conundrum.

In this one, 'length' has no functional relevance, but all the same, as Dac observed, the fuzzy continuity remains for those who would play (given standardised data).

Please don't take offence at my mutterings, keep the challengers coming, just give some thought to possible imponderables that some might see as 'insufficient data to play'.

Reasonable approximations should be assumed when "a customer goes into a jeweller". In any event, the jeweller could distort the links when joining to achieve the exact length if necessary. But five links are required to achieve a continuous chain.

Thanks for you comments which do not offend me at all.

As for units: (I am an engineer by the way) I have lived through dyne, pound, poundal, lbf and newton; the gm, pound, slug, lbm and kg; the erg, cal, BTU, ft lb and Joule. I will certainly try to abide to SI units in their 'preferred' format, but can't rule out occasional lapses.

aka "assume" = all wrong.... I'm afraid I don't understand this. Do you mean that the assumptions I gave were all wrong? Do you mean it is wrong to give any assumptions? What does aka mean (also known as?). In my student days it was common to be instructed for example to "assume ideal gas laws".

I will continue to submit challenges just as I will continue trying to answer them. Pity there isn't a GQ similar to the GA. Feedback on what was popular would be a help. The star rating seems to be seldom used.

Thanks again for your comments

SLR

Thank you for the question and the replies. I am enjoying them immensely.

We never made the conversion to SI, nobody, including the government, wanted to pay for it, for the time to get a "feel" for the units; I know what a ftkip feels like, literally, but I have not a clue what an Nm(sp?) feels like.

Hi SLR, I see we have lived through much the same.

"Lapses"; I have a few myself and embarrassingly, (given the cm wingeing), one is to use cc's when it comes to engine capacity. Over a litre - not a problem - but under, I just can't use "ml"; I badly want to use "cc", so like most - just leave it unsaid (between lapses).

"Assume" in my "= wrong" context, is that which people make in the absence of facts, guidance or will to be diligent/logical/inquisitive. For instance in the above unsaid, after say "650", in the small motor context, when it is "assumed" to mean cubic inches or litres, it may = wrong.

This is entirely different to 'guidance' by a lecturer on parameters to accept as "true" for the purposes of...

"Assume" in this context accomplishes two things. It acknowledges that some incongruity/complexity may exist and puts a boundary on the question, meaning don't delve into that.

E.g. what you posed in pendant;

"A customer takes a 100-link chain to her jeweler. Each link is 1 cm long"

Is 'bound' by

"to one end of the 100 cm chain".

This is a Perfectly Legitimate Boundary and I have no problem with that question in terms of clarity or your intent - but;

'Boundaries' may create their own problems.

With pendant, as written; if 100 links, 10 mm long, result in a chain of 1m: the link to link engagements are infinitely thin.

So 'assuming' "chain" means the common article's uniform section construction, how do links have mass? So how does the pendant (= 21 links) have mass? so why should it fall at all? Thereby a 'legitimate' alternate answer is 'infinity'.

"A chain of 100 links, 1 metre in length", may have been better.

By not supplying link length boundary, the infinitely thin argument is null.

My wording still leaves the problem of link form (eye radius) altering the assumed 1 m effective contact length with the felt in terms of 'leave' the surface.

Though "only accurate to two decimal places" nicely covers that.

It is difficult to protect yourself (even after spending millions of dollars) from every nit picker twit who just refuses to see the intent of the question. A way to minimise is to test the question. This site is actually fantastic for that. Not many questions survive here. Meaning; you're dam good at it.

I rate your joining question a "million dollar job".

There is only one correct answer and to a large extent only one 'wrong answer'. I.e. every other method of cut/join = 21 mins.

This is why I was happy to acknowledge Blink's cleverness, but couldn't give a GA as he 'cheated' the boundary ("it takes 1 minute to cut and open a link")

If there was a GQ, "joining" would have my vote instantly.

(Yes, aka was meant as "also known as". Strictly A.K.A. so my apologies for the jargon in sloppy acronym form) (I should have 'tested it' and spent more money on it)

I hope there is something of use in the above, and look forward to more questions - and don't let possible lack of "perfection" get in your way - nothing is.

Hey physicist, I see we are typing simultaneously but on different vectors again.

We both observed the pendant had things "not encompassed"

Jim introduced dynamic modeling, but on the available data and consistent necessary assumptions - got "nearer"- thats all.

Therefore I think it is a bit harsh on SL to demand a "challengers confirmation".

It takes edu millions of dollars to get one 4 option "pick-a-box" question statistically reliable. Poor SL is doing it for nothing / fun.

A Big Pity pendant got abusive, and no need to re-live that - ay?

How about we help with challenge questions?

It wasn't intended as a 'demand'. And SL certainly has nothing to be ashamed of: highly-reputed universities continue to set very similar questions (with the self-same issue) both as coursework and for examination- and SR's version was IMHO better worded than most of those. So a comment (from SR - because as the poser of the challenge he has some deserved authority) that the solution does not strictly correspond to the physical situation as described would be a bonus.

Regarding providing questions - I've done a few - and sometimes found the need to issue clarifications. I will doubtless attempt some more in the future (but I'll bounce them off you first if that's OK).

On the subject of "abusive" - either I missed it or interpreted it as (intentionally) silly banter rather than abuse.

Physicist you may bounce whatever you like off me, as may any (except 'transparent guests'). If I know - I will be delighted to share. If not, like many strings where I have nothing useful to contribute - expect silence, silliness but never disinterest.

Ref "abusive" - either I missed it or interpreted it as (intentionally) silly banter rather than abuse." Well you would - as none was intended.

It's not about you, me or SR, or any who can "fight all out" on issues and "facts" without rancor.

It's about how it can be read.

"It's about how it can be read."
As my wife never tires of reminding me (although I may not be too bad on factual precision) I'm a complete nincompoop when it comes to avoiding unintended emotional implications.

"nincompoop" - Ah the nostalgia that evokes. I'd be delighted to chat. Goto user profile.

No, I want the best quality. Which means finding the best (and probably therefore busiest) jeweller. So he'll want to minimise the time he takes.

Plus, planning for minimum disruption to pre-existing material is part of the skill of doing a first-class job.

That may apply in jewelery but from first hand experience with the pinheads in every other service industry I have been a part of the guy who gets the most done is nine times out of ten the sloppiest and usually has far lesser quality in his work than the guy who took more time and did it right the first time.

Myself as an example. I know I am no where near the fastest person in my fields of expertise. However I am known for being near the very top in the quality of the work I turn out.

If I did the chain it would take me 30 minutes but you could pull a truck with it when I am done!

Depending on the task, I can be fastest or slowest. If it is a where repetition makes you expert, I will be the slowest - and also not provide the highest quality.

(Recently, I have had the good fortune to employ an interoor decorator who worked as fast as any I have ever seen - and still produced a first-cloass finish)

They post the "official" answer in the same posting as the original challenge (between the challenge itself and its reply button). Sometimes it is later than promised. At least equally often it is incorrect.

Oh boy, waiting for a wrong answer sounds pretty disapointing, but thanks anyway.

Yahalsit

aah - so sweet...

Indeed Fyz, and a Guest that leads a post with "Show me your evidence" is a coward. No more no less.

Thank you for your vote of confidence. I was that guest - there was a system issue. Perhaps I should have delayed posting until it went away.

BTW, I couldn't quite make out your string-theory reference. Are there any open references that would help?

P.S. But I suppose you could say that hiding behind any alias is cowardice. I prefer the euphemism " valuing my privacy".

That would be an "ooops" (on my part ) - then again it illustrates the value of an avatar in interpreting thrust and nature of a post.

Ref 'ps'; there is a great difference between "avatar alias" (often quite necessary) and the zero at risk of "anonymous guest "

Ref string theory, surprisingly this is quite good - http://en.wikipedia.org/wiki/String_theory

And apparently I am out of date; there appears to be 6 at the Wiki minute.

I was very excited about this maybe 10 years ago, or was that 20. I'd be quite interested to see if you come to a similar conclusion on what overall conceptual non-acceptance is in the way of the thinking/solving.

Hi Kyzine

I'm familiar with most of that.
Most of the results I have found interesting (perhaps that should be comprehensible?) can be obtained in 6 complex dimensions, with the three+time being the observables.

What I missed was the connection with chains - unless you were casting chains as strings of pearls (before this swine-that-'flu).
BTW, given that I keep any intelligence I may have in my hands (it's moved up-and-outward somewhat over the years) some of my wife's jewellery does seem to have a remarkable resemblance to the unidimensional strings of string theory, in that the only place they can be undone is in my brane hands - and they miraculously refasten as soon as they leave them (and, at least so long as this remains the case, man will not be totally superfluous to the human species)

LOL, at your last Fyz

"What I missed was the connection with chains" - Hardly surprising as it was tenuous at best. I "decided" Williams 'string' comment meant; a link when cut, is no longer a continuum, but still may be termed 'a link' - to be analogous to string theory "argument", or as I like to call it "mathosophiser's"

I.e. is a "gap" ~= "unobservable continuum"?

"some form loops with pendants" , ,

should I have written pedants?

ROLMFAO - Twice! - No - still going - it's multiple. Top riposte Fyz!!!!!!