A survey of students' understanding of colliding bodies

The present article concerns the spontaneous conceptions held about the principle of action and reaction. A broad survey was conducted of students aged 12 to 21 years and teachers, and it was shown that the third principle of dynamics is in fact a great unknown, even for undergraduates following scientific courses and for many of the teachers of science. By defining "consistency" in the application of these alternative ideas, the existence of these conceptions in the form of authentic "minitheories" (implicit theories) can be proved. The empirical analysis of the genesis of this alternative scientific knowledge was further explored, together with the major difference between its epistemology and that of "official" physics.