Didactic reflections on some logical reasonings with the Newton's first law and his relation with the previous ideas of the pupils

Abstract

Students' previous assumptions that consider the force as the cause of the bodies' speed are widespread and very resistant to change. We reflect on some aspects about the contents of Newton's first law which appear in textbooks of secondary education, since they can be misleading if the teacher does not keep in mind some logical questions that, on the other hand, can lead to a better education in patterns of thinking, epistemological conceptions and students' knowledge of the scientific method. We analyze these logical aspects, where the teacher must pay more attention, in some secondary education textbooks. We show the convenience of introducing soon a definition of Newtonian force and prove its utility in the topic development.