[ RadSafe ] Re: SI units

[Cindy Bloom]

And I learned that a ton was 2000 pounds (versus 2240 pounds), but when I 
got older I found out there are short tons and long tons and both are 
called commonly called a ton.

At 06:37 PM 1/19/2007 +1000, Mark Sonter wrote:

>Deary me!
>
>I remember as a kid learning 12 inches equals 1 foot, 3 ft equals 1 yard 
>5-and-a-half yards one rod pole or perch, 16 ounces equals 1 pound, 2240 
>pounds one ton, etc etc; not to mention 32 poundals one pound force, and 
>something about slugs...and horsepower, BTUs, bushels, and acre-feet; but 
>maybe I'm wrong.
>
>No wonder NASA lost the Mars lander, if it was trying to work in both 
>imperial and metric....
>
>And then at university came the blessed discovery of first the cgs system 
>of units and then the kgs system, now SI.
>
>Then when I was teaching physics in Papua New Guinea, we, following 
>Australia, 'went metric', and at last gallons (two types, US and 
>Imperial), ounces (two types, Troy and Avoidupois), Fahrenheit, psi, and a 
>host of other awful units were rendered obsolete.
>
>Then I went off and did my Medical Physics, and learned pCi and rem, and, 
>God help us, Roentgens; and then I got beaten up by a curmudgeonly state 
>regulator who refused to talk in other than Bq and Sv (and rightly so, as 
>SI was now enshrined in national legislation).  There were a few cases of 
>mixed up units and accidentally ablated thyroids (not on my watch: I was 
>counting mSv in a uranium mine..)
>
>All I can say to our US colleagues is: try to embrace and encourage the 
>transition: make it as fast as possible: other countries have done it; it 
>will in the end save you immense brain energy on essentially wasted work; 
>and you (and the rest of the world) will then ultimately breathe a huge 
>sigh of relief.
>
>Mark Sonter