Deficiencias de comprensión y epistémicas de los estudiantes universitarios en la construcción de categorías explicativas sobre las relaciones trabajo-energía

The understanding of the generalized principle of work and energy is crucial to apply the relationships of work and energy in introductory physics courses and in the decision-making of the citizens in problems related to consumption and transfer of energy and machines. A questionnaire with open questions has been designed to detect students' learning difficulties. The analysis of the responses has been carried out using the phenomenographic methodology, which focuses on establishing interpretive categories at the collective level. The results obtained show that the students do not understand the concept of work and energy and do not recognize the need for modeling the analysis when defining a system. Some errors are more frequent in situations involving friction forces. Difficulties appears both at the conceptual and epistemological levels.