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Re: Low Concrete Quality

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>Not trying to be picky, just trying to understand.  How do you differentiate
>between kilogram mass and kilogram force if you are using the symbol "kg"
>for both?
There was a time when kilogram was used for both force and mass, just 
like the term pound was used. The force usage simply meant a force equal 
to the force of gravity on the mass of one kilogram.Very sloppy usage but 
you could generally sort them out in their context. About the only way I 
made sense of it was to hold my node and tell myself that 1 force 
kilogram is 2.20462... pounds and make the quantity into actual force 
units as fast as possible.

You can still find engineering publications which use kg/mm^2 as a unit 
of pressure or stress. My old fluids book (by Streeter, who was no dummy) 
quotes values for the universal gas constant of aa.b feet meaning aa.b 
foot-pounds(force)/pound(mass). I don't know if rocket people still speak 
of specific impulse as aa.b seconds meaning aa.b 
pound(force)-second/pound mass. I think dimensional analysis is another 
of those lost arts like calculation with logarithms, but it help get a 
lot of people through such inconsistencies.

Christopher Wright P.E.    |"They couldn't hit an elephant from
chrisw(--nospam--at)        | this distance"   (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)

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