ANALYSIS OF THE INTRODUCTORY DESCRIPTIONS OF UNIVERSAL GRAVITATION IN THE TEXTBOOKS - A Comparative Study of Foreign Textbooks of Physics at Upper Secondary School Level -

Abstract

We analyzed introductory description of the law of universal gravitation (hereafter UG) in foreign textbooks of physics at upper secondary school level. We investigated eleven textbooks which are used in Australia, China, France, FRG (West Germany), GDR (East Ge皿 1any),Indonesia, UK, USA, and USSR. Our study was made from five viewpoints: (1) knowledge of dynamics given before introduction of the law of UG: (2) the connection with Kepler's law; (3) the application of the history of science; (4) the process for deriving the law of UG; (5) the foundations of the universality of gravity. Our findings are as follows: (1) There are a variety of descriptions of UG in these textbooks; Among them, french "PHYSIQUE" describes UG simplest, treating it as just one of examples of forces, while USA's "PROJECT PHYSICS" deals with UG in most detail, regarding the law of UG as very important not only to understand the natural world but to illustrate the scientific method. (2) In many of these textbooks, the law of inverse-square and the proportionality to mass for UG are derived simultaneously from Kepler's third law, as done in Japanese textbooks of today. On the other hand, in a few textbooks such as UK's "NUFFIELD PHYSICS", the proportionality to mass is derived from the fact that an accerelation of gravity on the earth is independent of the mass of a relevant object. We consider that the latter derivation is more reasonable than the former. (3) Generally speaking, more acceptable to students are the textbooks where the law of UG is derived in more accordance with "PRINCIPIA" and where more historical view of science is adopted.