Trends in Contemporary Textbooks

This chapter deals with concepts of energy and formulations of the conservation principle in bachelor-level physics textbooks. Each of the propositions under analysis, concepts and principles, is linked to a similar proposition from the nineteenth century. This connection makes it possible to understand that the present trends in textbooks stem from currents of thought from the past, about which contemporary physicists do not seem to be aware. Textbooks generally use Mayer's or Joule's calculations of the mechanical equivalent of heat and Joule's paddle wheel experiment to introduce the concept of energy. This experiment has been reassembled, with the calorimeter and paddle wheel replicated from the original. The results obtained with this apparatus and with those based on the Joule experiment schemes presented in the textbooks, make it possible to clarify some aspects of the Joule experiment and improve the textbook presentations.