Re: What are measures of mass and weight?

From: Gene Nygaard (gnygaard_at_nccray.com)
Date: 06/20/04 

Date: Sun, 20 Jun 2004 10:54:37 -0500

On 20 Jun 2004 06:21:33 -0700, dcshead@charter.net (Donald G. Shead)
wrote:

>What are measures of mass?
>
>The only measure of mass that I can think of is _inertia_: Which has
>units expressed in slugs; grams, and kilograms:

Also pounds, ounces, hundredweight, pennyweight, stone, tons of
various sorts. Also hyls (aka metric slugs, mugs, or TME from a
German acronym).
>
>Slugs are mathematical ratios of the net force [f], exerted on and/or
>by an object, body or mass of matter [m], divided by the acceleration
>[a] that it causes: m = f/a.
>
>Grams are mathematical ratios of the net force [f], exerted on and/or
>by an object, body or mass of matter [m], divided by the acceleration
>[a] that it causes: m = f/a.
>
>Kilograms are mathematical ratios of the net force [f], exerted on
>and/or by an object, body or mass of matter [m], divided by the
>acceleration [a] that it causes: m = f/a.
>
>The kilogram in the archive at Sevres, France is an artifact built as
>close to that mathematical ratio as technology can make it, but
>differs enough that it had to be put to vote by the member countries
>whether or not it was acceptably close. It was accepted, and is now -
>by decree - the standard kilogram [k].

Totally wrong. The target of the manufacturers of the International
Prototype Kilogram, as well as its two siblings maintained by the
BIPM, and about 40 more that serve as National Prototypes, was not
some goofball ratio, some figment of Dense Donny Shead's imagination
that would be of absolutely no utility in construct a standard, and
something that didnt' exist even 10 years ago.

Rather the target for the new standards constructed after the Meter
Convention (or Treaty of the Meter) of 1875 was the old standard: A
platinum cylinder constructed by the French in the 1790s and
maintained by them as the standard for the kilogram until the new
standards were put into place 90 years later. That's what they aimed
at, what they had to come "close enough" to.

>What are measures of weight?
>
>The most common measure of weight that I can think of is the force
>exerted between the terra firma surface of a planet like Earth, and
>the stuff resting on them.
>
>In order for matter to exert force, and have weight, it must have
>something to bear against: that's why free bodies are "weightless".
>
>Units of force are pounds, dynes and newtons; but that's a long story
>which I'll continue with another time.

Poundals are another unit of force, of course. They are the units
which accelerate the base unit of mass in this absolute fps system.
Fill in the blank for us, Dense Donny: The base unit of mass in this
oldest coherent system of English mechanical units is the
____________________.

Gene Nygaard

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