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-   -   Units (https://www.pprune.org/engineers-technicians/214006-units.html)

Genghis the Engineer 3rd Mar 2006 21:14

Units
 
I'm having a bit of a rant, what do you folks think.

Units....

- I routinely do sums in metres, feet, inches, millimetres, kg, kgf, lb,lbf, psi, Pa, litres, US Gallons, °C, °F, K, and on a few unhappy occasions, slugs. I do not complain about this (well, maybe about slugs) I have taken the trouble to learn all of these systems and how to convert between them, I accept that the use of multiple unitary systems is just how the world is - at-least the aviation world.

Yet the education systems (and I fully accept that I'm a product of this myself, but got retrained) in the UK and Europe are hellbent on telling everybody that imperial units are obsolete and shouldn't be used. Something similar (maybe not quite so aggressively) goes on in North America with imperial units - they get really worried if you try and do calcs in Newtons!

Should the world at large just accept that there are different systems in use, and live with it?

G

[/rant]

Yarpy 3rd Mar 2006 22:03


Should the world at large just accept that there are different systems in use, and live with it?
Of course they should. Trouble is, their is a dogma these days that is trying to make everything and everyone homogenous. Everything has to levelled towards the norm in a world where everything and everyone is different.

I don't know why life has become like this. I know I don't like it.:}

TURIN 3rd Mar 2006 23:29

I was taught at school in metric, served my apprenticeship in imperial, pump fuel on to most aircraft in metric and the yanks want it all back in (US) imperial again!!!! :\ :eek: :mad:

An accident waiting to happen?

I have ten digits on my hands, I'll go with metric anytime.:O

noisy 4th Mar 2006 11:10

Go Googling for a little piece of software called convert1.exe
It will do most of the things you want, although you will need some kind of PC to run it on.
Wish I'd known about it at university.

Genghis the Engineer 4th Mar 2006 12:15

That's not the point is it - I have shelves full of data books that do that as well.

My problem is with an educational system that refuses to accept that there are a plethora of systems, and teaches people how to understand and deal with it.

G

Krystal n chips 4th Mar 2006 13:15


Originally Posted by Genghis the Engineer
That's not the point is it - I have shelves full of data books that do that as well.
My problem is with an educational system that refuses to accept that there are a plethora of systems, and teaches people how to understand and deal with it.
G

And therein Genghis lies the root cause I would suggest. The objective within the primary / secondary educational system is, seemingly, to produce a student with an acceptable grade and hence fulfil a quota. To do this however, you have to discard any aspects that may not be considered as being relevant--or just plain difficult of course:rolleyes: and concentrate on getting little Tabatha and Tarquin through the exam--irrespective of whether they have actually learnt anything of course--or have the wish to which is probably also as pertinent.

Turin,
" an accident waiting to happen"---er, I think it already has --a certain 767 in Canada?--not quite as a result of the conversion you mentioned ( and yes, it used to p$$s me off as well ) but" units of confusion" certainly contributed as I recall.

Rigga 4th Mar 2006 20:22

The problem is that EU schools don't teach anything other than metric - and so they won't recognise other units for school purposes - whether they are used or not!
I was taught, in the 70's, to use Imperial measurements but we were also informed of, and used, the new metric system - only because it would come in to use very soon after the introduction of new pounds and pence. (with no shillings)

yeah, right!

As Krystal intimates; If it doesn't add to the bottom line of mandated educational requirements - why do it?

Would you do Modifications that you didnt need to?

Golden Rivet 5th Mar 2006 07:33

If your Maths is up to speed it doesn't matter what units are used.

A Professional Engineer such as Genghis shouldn't have any problems with a few simple calculations :rolleyes:

Genghis the Engineer 5th Mar 2006 07:50


Originally Posted by Golden Rivet
If your Maths is up to speed it doesn't matter what units are used.

A Professional Engineer such as Genghis shouldn't have any problems with a few simple calculations :rolleyes:

True enough now, but the 21 year old Genghis, just graduated from one of Britain's better universities to be honest didn't. Nor, I think do most of the current generation of graduates, and certainly not any significant proportion school-leavers. It worries me.

G

Krystal n chips 5th Mar 2006 08:27

If it's any consolation Genghis, the problem is more acute than you realise. I had a couple of "conversations" with "yoof " at British Garse and asked ( having been offered utter :mad: in terms of statistics as to how my greatly inflated bill had actually bee derived ) did they know about exponential smoothing ?--short answer was "Wot ? "--both times.

barit1 5th Mar 2006 13:30

To the REAL engineer, dealing with Kpa, psig, psid, psia, BTU/lb, or gram-inches is all in a day's work. :uhoh:

When first writing dual-dimensioned torque values, we determined the correct SI units were Newton-Meters. The French said "Eh??? We use Kg-Meters!"

I suspect the educators prefer only one set of units to avoid showing their own shortcomings. :ugh:

Personally, I enjoy the challenge of units conversion, if only to keep me from turning into a new-and-improved Murphy. :)

john_tullamarine 5th Mar 2006 22:38

(a) as a raw engineering graduate I spent about two months playing with a whole bunch of different systems to acquire a comfortable understanding of, and facility for, conversions which the undergraduate system had only addressed imperfectly.

(b) I don't see the role of the education institutions being to waste time on teaching other than the principles of unit conversion .. the former is an Industry, rather than Institution, concern. (Genghis will have his own views on this but that is another matter). It makes a lot of sense for the institution courses to use one consistent set of units .. doesn't matter much which set but that which is closest to standard in the particular country makes a good starting point ...

(c) all of us get rapidly comfortable with that set of conversion factors which we use day in day out. The important thing is to be VERY comfortable with deriving those units .. how many times have we had to do just that because the list of data conveniently to hand didn't have the one conversion we needed just then ?

(d) the Industry workload imposed by use of a multiplicity of units is both silly and dangerous, especially when something unusual is happening (isn't that more common than we might like ?) and the folk involved are in the normal pressure cooker environment to get the bird out on time.

(e) if one is going to use multiple systems, such should be done with procedural rigour.

(f) the Gimli Glider has been mentioned and there are numerous other happy- and not-so-happy-ending story equivalents around the traps.

(g) working up conversions rigorously doesn't take much nous in maths but it does call for pedantic housekeeping.

(h) and I think that most of us old codgers are desperately worried about the new chum (ie last 10-15 years) who is trained to push buttons with all the attendant GIGO risks .....

.. and it does keep life interesting periodically coming across new, bigger and brighter boxes of units from time to time.


But I am a bit confused on one point .. who doesn't use slugs ? Whatever is the world coming to ?

Blacksheep 6th Mar 2006 02:51

Its quite possible that educators are the only comprehensive users of Systems International(e) units.

UK was supposed to have gone Metric in 1971, but in the 21st century whenever I'm in UK I still have to mentally convert to driving in miles per hour and buying things by the pound. Money was of course, successfully decimalised - much to the chagrin of Mrs B who had to learn LSD (pounds, shillings and pence - remember those?) at school in Malaysia, even though the local currency was Straits Dollars and Cents. I remember once asking for twelve feet of dowelling in a hardware shop. I was told scornfully that it was "measured in millimeters now" but when I came to pay for it, the price was thre'pence a foot!

Like most people I've learned to mentally approximate pretty well; when in England, doing a hundred 'Klicks' is about sixty m.p.h., half a kilo becomes 'a pound o' mince' and a litre of milk is - well b*gger me! - a litre of milk! Whatever happened to the good old pinta?

But approximation is no good when you're committing engineering. Do the sums properly, on a slide rule, and hope you've got the conversions right.

Genghis the Engineer 6th Mar 2006 07:09

Believe it or not, the law in the UK prohibits the use of any units other than miles, yards or feet on road signs.

The law also requires fresh produce (fruit and veg, etc.) to be sold in kilogrammes.

What the law says about education I'm unsure, but it's almost certainly incompatible with at-least one of these two facts.

G

Rigga 11th Mar 2006 21:29

Good 'Ole Tesco sells it's milk in bottles of 2.2 Pints (1 Litre) and we buy petrol by the Litre but expect to get 55 Miles to the Gallon?

Motoring magazines now quote accelleration times to 62 mph (100kph)

In Holland and Germany you can ask for a "Pfund" or HalbPfund" of meat at the market (and you get 500gms/250gms) A "Viertel" (1/4) is normally sold as 100gms.

Why, even after the law changes, can't we in UK ask for a pound of meat and be served 454gms?

I believe there is mow discussions at high levels of changing road signs to Kilometers in time for the london Olympics?
I can see more partial remedies to be enacted upon as dictated by the Greater London Management - and yet more confusion for the rest of us, I think.

barit1 12th Mar 2006 00:59

Conversion tables - always useful:
 
1. Ratio of an igloo's circumference to its diameter = Eskimo Pi

2. 2000 pounds of Chinese soup = Won ton

3. 1 millionth of a mouthwash = 1 microscope

4. Time between slipping on a peel and smacking the pavement = 1 bananosecond

5. Weight an evangelist carries with God = 1 billigram

6. Time it takes to sail 220 yards at 1 nautical mile per hour = Knotfurlong

7. 16.5 feet in the Twilight Zone = 1 Rod Serling

8. Half of a large intestine = 1 semicolon

9. 1,000,000 aches = 1 megahertz

10. Basic unit of laryngitis = 1 hoarsepower

11. Shortest distance between two jokes = A straight line (sheesh!)

12. 453.6 graham crackers = 1 pound cake

13. 1 million-million microphones = 1 megaphone

14. 1 million bicycles = 2 megacycles

15. 365.25 days = 1 unicycle

16. 2000 mockingbirds = 2 kilomockingbirds

17. 52 cards = 1 decacards

18. 1 kilogram of falling figs = 1 Fig Newton

19. 1000 milliliters of wet socks = 1 literhosen

20. 1 millionth of a fish = 1 microfiche

21. 1 trillion pins = 1 terrapin

22. 10 rations = 1 decoration

23. 100 rations = 1 C-ration

24. 2 monograms = 1 diagram

25. 4 nickels = 1 paradigm

26. 2.4 statute miles of intravenous surgical tubing
at Cornell University Hospital = 1 IV League

:ok:

Perrin 12th Mar 2006 09:34

PERRIN
 
REMINDS ME OF WHEN AS A AMERICAN WHO CAME OVER AND STARTED WORK AT SCOTTISH AVIATION
THEY TOLD ME TO GO AND BUY WHITWORTH,BSF AND BE SURE TO ALSO BRING MY AF SPANNERS, LITTLE DID I KNOW THAT I WOULD NEED SOME OF THEM AGAIN WHEN THE DREADED ATP HIT THE MARKET, TRY CHANGING A BRAKE CONTROL VALVE USING A ADJUSTABLE SPANNER GREAT FUN IN THE RAIN.:{

camlobe 12th Mar 2006 16:46

Within my professional working enviornment, I work with Imperial, American and SI units. The Imperial system used includes Whitworth (BSW and BSF) and BA, Unifiedthread, UK gallons and pounds. The American system used includes AF, AN, MS, US gallons. The Metric system as we all know includes mm, Kg, N/M etc etc etc.

OK, so I can use all these systems. Getting back to the point of this thread, YES I would like to see one standard system of units used. If for no other reason, it would stop Mr Snap-on etc making three times the money out of me.

Windy Militant 14th Mar 2006 12:12

What's with all this Centimetres nonsense! I was taught that the approved ISO unit was the Metre and that you worked in multiples of a thousand ie Kilometers or Milimetres.
You don't get mass expressed as Centigrams you get Miligrams, Grams or Kilograms.

So why do schools insist on using centimetres?

Mind you I still tend to mentally convert to feet and inches, 9/64ths of b*gger all sounds so much better than 3.571875th of b*gger all ;)

forget 14th Mar 2006 12:22

I'll post this at every chance I get!

Who said, on metrication -

“Nothing is more contrary to the organisation of the mind, of the memory, and of the imagination. The new system of weights and measures will be a stumbling block and the source of difficulties for several generations.
It's just tormenting the people with trivia”.

No less than Napolean Bonparte! :ok: :ok:


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