Students’ Difficulties in Applying the Law of Conservation of Mechanical Energy: Results of a Survey Research

The purpose of this study was to explore the effectiveness of the conventional high school instruction about conservation of mechanical energy in Canton Sarajevo. To that end we tested 441 high school students from six different schools in Sarajevo (Bosnia and Herzegovina) for their competence to apply the law of conservation of mechanical energy. Concretely, students were expected to solve 5 open-ended tasks that covered conceptually different situations. In each task we asked a set of sub-questions to check whether the students possess all the prerequisite sub-competencies for systematic reasoning about conservation of mechanical energy. In addition, we investigated how students’ ideas about conservation of mechanical energy were affected by the choice of the physical system, as well as by the choice of the observed time interval. Data analysis was performed on the level of individual tasks. The students’ written answers were analyzed and the frequencies of most prominent student responses were reported. Generally, it has been shown that most high school students from Sarajevo fail to identify and distinguish internal, external, conservative and non-conservative forces. Also, many students think that applicability of the conservation law does not depend on the chosen physical system and its evolution over time. We could conclude that high school students’ use of the conservation law is mostly based on remembering similar problem solving experiences, rather than on relevant strategic knowledge.