daN/mm -- it's not what I thought!!!

Yup, just another danm unit!

In the early 70s I read a machine Design article (I had a subscription since I considered it as one of the best) where it was written that "metrication" in the USA will be finished in about 10 years.

If you would not stay stuck with the old units you would not be so p$$$$d off as you are. Inertia and conservatism does not pay and the unit is NOT used ONLY in France.

I, for instance, do not complain but when I have to deal with BTU, °F, ksi and some other units officially not any more valid according to international agreements (signed by ALL industrial countries even by the US standardization organizations) I take a deep sight and look in the conversion table and do the work. Of course I make a silent comment which I shall not reproduce since it has to stay silent.

To your information: Before the Newton became compulsory the most used unit was the Kgf which means the kilogramforce. When the new system was introduced some had difficulties to have the right feeling for new unit (1 N is the force to imply an acceleration of 1m/s² to a mass of 1kg). Since in the metric system g=9.81 m/s² the daN is a force unit with a magnitude near to the previous unit and thus allowed a better feeling. This is the origin of this stupid unit. By the way do you know how the foot was defined ? and the inch ? history of units is quite funny.

I do not defend the daN since I do not use it I quite soon got accustomed to N and kN or MN when I had to design hydraulics for 600.000.000 N. It was quite amusing since the docs for the pump I has to use gave the pressure as 10 ksi.

Sticking to a "normal" N/mm unit (181.92N/mm ) would seem in this instance to make more sense.

There is a plethora of Metric/Si sub units.

The web query " What the hell is a "aN" "... could have got you

Measurement unit: attonewton

Full name: attonewton

Plural form: attonewtons

Symbol: aN

Category type: force

Scale factor: 1.0E-18

›› SI unit: newton

The SI derived unit for force is the newton.
1 newton is equal to 1.0E+18 attonewton

It's been a long time since I saw the last invocation of a double prefix, and the only one I'm truly accustomed and still rather fond of was the "μμF" long since deprecated to the "pF" in every parts catalog I've seen for the past 30 years.

So while I might have interpreted 18.192 daN/mm could have been interpreted as "deci-atto Newton per millimeter" we gotta think about that *miniscule* rate as being much less than the Brownian motion on a dust particle in cold Helium at a few mT(abs) milliTorr (absolute) or is that a fraction of a Pascal, and reject it out of hand. :^)

OK, Seriously, it appears that "da" became official in 1960??? Does this mean I have an actionable claim against my school system for using textbooks that were more than a "_decade_" out of date??? {no pun intended}

Just as 10^-18 male children = 1 attoboy.