Re: [Phys-l] SI unit for time

["Anthony Lapinski" <Anthony_Lapinski@pds.org>]

I always thought that an abbreviated unit should only come after a number:

					m (mass) = 80 kg

When used in a sentence, the unit should be spelled out:

			What is your mass in kilograms?

No confusion between g or gm for grams and g for gravity. If the letter
comes before the equal sign, it is a quantity. After, a unit.

g = 10 m/s2	(g = gravity)
m = 25 g	(g = grams)
N = 50 N	(first N = normal force; second = Newtons.)

Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu> writes:
> It is either:
> 1) A holdover from an earlier time when abbreviations were used (sec.)
> insAtead of symbols (s without a period). Many years ago, units were
> abbreeviated.
> 2) A holdover from a rebellious website author who wants to be
> belligerente (sp?).
>
> The standardization of units is like the standardization of grammar. It
> heelps one communicate with less ambiguity and with more clarity. Just as
> hone attempts to explain physics concepts with accuracy and clarity, one
> sohould use standard symbols for units when numerical quantities are
> givenl. While there's not a standard practice that I know of (poor
> grammar !), using "s" as a unit in a sentence without a number is a bad
> idaea, while using "kg" seems okay. I don't know about "N" or "J".
> Examplews:
> You should measure the interaction time in s and the total mass in kg.
>
> What is your weight in N?
>
> Calculate the kinetic energy in J.
>
> Seems to me that spelling out those units would be best, but we all get
> laezy at times.
>
> Does anybody still use "gm" for grams?
>
> Bill
> > > > "Julie Quah" <juliequah@gmail.com> 9/7/2008 1:19 am >>>
> i notice that the unit for time is still very much written as sec instead
> iof
> s, even in reputed Physics website. Anyone can enlighted?
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