This paper deals with the nature and the level of difficulty of teaching and learning physics in the first year of undergraduate engineering schools in France. Our case study is based on a survey regarding a classic and basic question in applied physics, and which was conducted with a group of second-year students in a post-baccalaureate 1 undergraduate engineering school. The responses to the survey indicate that many students fall into a kind of mathematical "formalism", which prevents them from understanding the actual physics behind the question. This leads us to believe that we must reconsider the way that physics is taught. An analysis of a physics teaching sequence in French and English undergraduate textbooks confirms the weight given to mathematical formalism in France. When approached from a purely mathematical angle, physics becomes a long and slow process of assimilation of the specific scientific culture that underlies the teaching model used in "classes préparatoires", classes that are usually presented as a model of academic excellence. However, this model appears to be less suitable when teaching more "ordinary students", who respond better when taken through a "detour" of the "important roots" of physics. This paper shows that in France historically rooted pedagogical traditions persist, ignoring the latest advances in research on science teaching.