Imperial and/or metric units. Discussion on the use and teaching of

[whole diary]

[Btline]

There are clear benefits of using metric for construction purposes.
(despite the fact that everyone uses ft for height, oz for babies and lbs for weight...)

In schools, clearly both should be taught, with an emphasis on converting without a calculator.

But I don't see any benefit of adding confusion by switching speeds to km!
It was just like when they switched to litres for petrol. Now I have mpg and litres mixed. Why not just sell petrol in gallons?

The gov has ruled out any switch on the road (thank goodness, how much money would it cost to yank out every 100 yds to go sign and move it 10 yds!)

[chuffed]

All those of you that went to secondary schools in the 50s and 60s in the Bristol aerial ( ahem!) must remember the back covers of your exercise books! They had all the arithmetical tables of number,  imperial measurements of distance, including rods, poles and perches, together with avoirdupois (weight). Not forgetting the sketch map of Fifty miles around Bristol, which certainly burned into my brain !
Even if we were just colouring the map in, during a wet playtime, we were learning where places were in relation to each other. As a junior school teacher of 30 years standing ( retired 10 years ago) I can see the value of reintroducing it,the updated metric tables and the map even now.

[TonyK]

I was in Waterford, Republic of Ireland, some years ago. Around the area, there had been an attempt to convert to metric. Some direction signs were in miles, some in kilometres. Some looked fairly new, but bore only a number,  giving ni indication which stable they belonged to. When I asked what the plan was, I was told that no-one really knew, but it didn't matter, as none of them were remotely accurate in either denomination. Set off, and you'll get there, was the sage advice. I enjoyed my stay greatly.

Who recalls the Metrication Board's helpful rhymes from the early 1970s?
"Two and a quarter pounds of jam
Weighs about a kilogram"

"A litre of water's
A pint and three quarters"

And my favourite bit of official doggerel:

"A metre measures three-foot three
It's longer than a yard, you see".

Meantime, it's about time we joined our European neighbours in having all cars driven on the wrong side of the road. If it's a success after a month, the lorries and buses could move over as well

[Electric train]

Meantime, it's about time we joined our European neighbours in having all cars driven on the wrong side of the road. If it's a success after a month, the lorries and buses could move over as well

And a month after by motor bike and push bikes 

[bobm]

As I was once told, in no uncertain terms, a woman will never quote her measurements in anything other than inches.  (especially if the centimetre equivalent is over 100)

[Chris from Nailsea]

Hmm ... I wonder if anyone would dare to ask member broadgage for his views on that, erm, rule? 

[TonyK]

There are clear benefits of using metric for construction purposes.
(despite the fact that everyone uses ft for height, oz for babies and lbs for weight...)

You generalise, btline.

FT,N! (1.88m)

[Chris from Nailsea]

All of my domestic DIY construction and repair activity is calculated in feet and inches - that drives my teenage son mad, as he doesn't understand a word of it.

Chris, age 55, 6 ft, 34 in waist (on a good day). 

[grahame]

Chris, age 55, 6 ft, 34 in waist (on a good day). 

Congratulations on your recent 200th Centaday!

Edit to correct units

[Btline]

Off course, Weight Watchers encourage the use of metric, as you lose weight faster...

[Chris from Nailsea]

Chris, age 55, 6 ft, 34 in waist (on a good day). 

Congratulations on your recent 200th Centaday!

Edit to correct units

I've just weighed myself on the bathroom scales, and I'm now 11st 9lbs (or whatever that is in kilometres). 

[stuving]

It is still  a pity that so many commentators can't write units correctly (capitals for proper names, l.c. for multiples) and that power stations are rated in 1000's of homes powered. What is the conversion?

It's all part of the dumbing-down process. The TV-watching public are supposed to be unable to cope with facts, especially ones with numbers in, so these have to be taken out wherever possible. It even happens on BBC2/4 or C4 documentaries, where you suspect the viewers are likely to be at least as numerate as the programme makers.

The recent "Cloud Lab" proigrammes were particularly bad; you could see how the meteorologists had been leaned on to dumb down their scripts. So they tried to explain how much latent heat the moisture in a cloud could deliver by converting to electricity in "houses for a year". Pointless, as it is so hard to comprehend how big a cloud is.

I think they missed a trick here. I've been puzzled for a while why latent heat is so rarely converted into a temperature rise. I think the result is really rather startling - does anyone agree?

What you do is divide the latent heat of evaporation by the specific heat. The interpretation of the result is this: if the heat it takes to convert water to steam (or that is released in condensing it) is used to heat that water (or steam), how many degrees does it heat it by? The answer is: 540^C* (or 1120^C for steam). In a cloud, the water drops out as rain and leaves its heat behind, heating mainly air. The same equivalent temperature rise then is even bigger: 2277^C. So if you condense 0.5% water vapour by weight from air, it heats the air by 11 degrees! (e.g. start at a dew point of 12^C, and cool to 0^C). I think that explains a lot about the driving force behind tornadoes, hurricanes, and lesser storms, but I've never seen it done.

* Strictly speaking the unit of temperature difference is K (Kelvin), and ^C are only used for the scale with a defined zero. There was a long and rather Lilliputian dispute about this, and the acceptability of C^ and ^K.

[grahame]

I've just weighed myself on the bathroom scales, and I'm now 11st 9lbs (or whatever that is in kilometres). 

73,935,000 milligrams

[Chris from Nailsea]

 

[onthecushions]

What you do is divide the latent heat of evaporation by the specific heat. The interpretation of the result is this: if the heat it takes to convert water to steam (or that is released in condensing it) is used to heat that water (or steam), how many degrees does it heat it by? The answer is: 540^C* (or 1120^C for steam). In a cloud, the water drops out as rain and leaves its heat behind, heating mainly air. The same equivalent temperature rise then is even bigger: 2277^C. So if you condense 0.5% water vapour by weight from air, it heats the air by 11 degrees! (e.g. start at a dew point of 12^C, and cool to 0^C). I think that explains a lot about the driving force behind tornadoes, hurricanes, and lesser storms, but I've never seen it done.

Another problem is that the latent heat or enthalpy of condensation is pressure dependent, becoming zero above the critical pressure, where the density of water and steam are equal.

Yet again, latent heat was the Achilles heel of Swindon's steam engines as it all had to be wasted up the chimney, eqalling perhaps 80% of the fireperson's efforts. A final example is in the late and lamented destruction of Didcot A's cooling towers or latent heat rejection plant. We may come to regret this.

OTC