[USMA:22967] Re: 'metric' versus 'SI'

[Joseph B. Reid]

Joseph B. Reid

Terry Simpson wrote in USMA 22953:

I read:
"the International System of Units (SI), which is the modern
form of the metric system."

and I conclude:
1. SI unit = unit of the 'modern form of the metric system'
(we appear to agree about this).

2. Non-SI unit = not a unit of the 'modern form of the
metric system' (we do not appear to agree about this).

Am I wrong in my second conclusion?

Yo9u are wrong See Tables 6, 7, and 8 of the "The
International System of Units".
Table 6. Non-SI units accepted for use with the Intenational
System
Table 7. Non-SIunits accepted for use with the International
system, whose values in SI units are obtained experimentally.
Table 8. Other non-SI units currently accepted for use with the
International System..

It is the units of Tables 9 and 9 that should be avoided, although
many people  still  use them.
    Table 9. Derived CGS units with special names
    Table 10. Examples of other non-SI units

Thank you for your reply. I see that table 6, 7 and 8 are non-SI units
that are 'accepted for use'. I see also that tables 9 and 10 are non-SI
units that are 'not encouraged'. We agree about all these being
'non-SI'. The problem only comes into play when we start using the term
'metric system' which is not mentioned in these tables. I need to see a
currently valid definition of 'metric system'.

If found the phrase 'metric system' here:
"the International System of Units (SI), which is the modern
form of the metric system."

I conclude:
1. SI unit = unit of the 'modern form of the metric system'
(we appear to agree about this).

2. Non-SI unit = not a unit of the 'modern form of the
metric system' (we do not appear to agree about this).

When you say: "You are wrong" I take it to mean that either the
definition or one of my conclusions is wrong but I do not know which it
is, can you tell me which?

I appreciate you taking time to clarify this. I would be happy if
anybody else in the list could clarify this for me.
--
Terry Simpson

It is your second statement that is too restrictive. You would be laughed out of court if you eschewed litre, degree, tonne, hectare, nautical mile, knot, bar, angstrom, and electronvolt.