May I take Eugene up on some points? Given that the Draft "knowledge of physics and mathematics beyond a usual high school education requires knowledge of physics", it is entirely appropriate that the historic perspective be given prominence in the Draft.
In my view, Version 9 of the SI Brochure should be structured such that a reader who is embarking on an undergraduate course could be given the brochure and be told "On a first reading, skip sections X, Y and Z - you don't really need them for the rest of the brochure to be useful. One way to do this would be to interchange Sections 2.4 and 2.5 and that each subsection of the "Historic perspective" finish with the new/current definition of the unit preceded by a one-line justification for the new definition. The section "Historic perspective" could be renamed "Development of the base units". The new Section 2.5 (formerly 2.4) would expand on those definitions. The current sections 2.4.8, 2.4.9 and 2.4.10 could remain as part of section 2.4. Thus our student who is starting an undergraduate course would be advised to "Read the brochure, but skip section 2.5." [Section 2.4 in the current draft]. For the record, I tutor British "A" Level students (aged 16-18)on a one-to-one basis in physics and maths. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of mechtly, eugene a Sent: 06 January 2014 05:28 To: U.S. Metric Association Cc: mechtly, eugene a Subject: [USMA:53491] Draft for chapters 1-3 of the next SI Brochure My first reactions to the Draft are: 1. Understanding the Draft requires a knowledge of physics and mathematics beyond a usual high school education. 2. Although this level of complication may be necessary to base SI entirely on defined numerical values of fundamental constants, greatly simplified explanations will be necessary to teach SI to elementary and secondary students. 2. The historical facts of the evolution of cgs units, mks units, and mksa units into SI units belongs in appendices, as in previous editions of the Brochure, not in the main text of the Brochure. 3. The letters "SI" are a "symbol" as are s, m. K, symbols for the SI Prefixes, etc., not "abbreviations." 4. A new name and symbol for the kilogram (kg) is needed to emphasize that the kilogram is *the* coherent unit of mass in SI. Eugene Mechtly
