A note to the teacher and student regarding background information and pedagogy.
Nearly every physics textbook has an adequate section regarding Newton’s universal gravitation, Cavendish’s work and an introduction of Kepler’s laws of planetary motion. Therefore, in this work I will not attempt to teach those topics, but will rely upon the fact that the student has a basic understanding of the physics involved with these three men’s work as it pertains to an understanding of gravity. Many text books do not contain a treatment on current understanding and development of the ideas regarding gravitation. Those that do, often place it as footnotes to a chapter or as chapters late in the text that a typical class may never get to. This chapter of the Virginia Physics Flexbook will attempt to address our changing understanding of gravitation and in doing so also introduce the student to a few interesting areas of astronomy and cosmology. This chapter should be an appropriate extension to a study of Newton’s Universal law of Gravitation. This chapter deals with gravitation from a purely conceptual approach. The appropriate high school level mathematical treatment would pertain to Newton’s Universal Law of Gravitation and it is assumed the student will study this from his traditional text or with her teacher
The chapter is set up in a dialogue style. This has a wonderful heritage in physics going back to Galileo’s Dialogue Concerning the Two Chief World Systems published in 1632.
It is my practice and suggestion that a treatment of universal gravitation in high school physics class be approached in an historical manner starting with Aristotle and extending to as near the present understanding as possible. In treating it in this manner the following Physics Standards of Learning for Virginia may be addressed:
PH.1 The student will plan and conduct investigations in which
e)the limitations of the experimental apparatus and design are recognized;
f)the limitations of measured quantities are recognized through the appropriate use of significant figures or error ranges;
PH.3 The student will investigate and understand how to demonstrate scientific reasoning and logic. Key concepts include
- analysis of scientific sources to develop and refine research hypotheses;
- analysis of how science explains and predicts relationships;
- evaluation of evidence for scientific theories;
- examination of how new discoveries result in modification of existing theories or establishment of new paradigms; and
- construction and defense of a scientific viewpoint (the nature of science).
PH.4 The student will investigate and understand how applications of physics affect the world. Key concepts include
- examples from the real world; and
- exploration of the roles and contributions of science and technology.
PH.12 The student will investigate and understand how to use the field concept to describe the effects of gravitational, electric, and magnetic forces. Key concepts include
inverse square laws (Newton’s law of universal gravitation and Coulomb’s law)