This Israel-based investigation of introductory-course students' (including 48 non-science majors) understanding of energy concepts demonstrates that many students develop incomplete and incorrect understandings of gravitational potential energy.
- In response to feedback from students' answers, teachers should derive further questions to elicit misconceptions and clarify students' understanding of physical concepts.
- When describing the simple harmonic motion of a pendulum or frictionless bowl at least one in eight students predicted that the final height of a swing would be greater than the initial height.
- Students use a colloquial association of energy with activity.
- Students can confuse energy, force and momentum in explanations.
- Students believe that energy is used up or consumed in processes.
- Students can believe that gravitational potential energy is influenced by the motion of objects, for example, two balls of identical mass and height have different GPE if one is moving, and the other is at rest.
- Students can believe that gravitational potential energy is influenced by support – a ball resting on a surface does not have gravitational potential energy.
The study was designed to document and analyse student understanding of energy concepts and characterize student thinking.
Data were collected by analysis of student responses to free-response written questions based on course examinations and ungraded quizzes. The questions were constructed so that incorrect answers would correspond to the incorrect ideas which had been observed in informal interactions with students. Student explanations of their answers were classified and assigned codes so that they fell into categories.
Before the written questions, all students had been taught explicitly the formulas for gravitational potential energy and kinetic energy, with particular emphasis that gravitational potential energy depends on mass, height above a reference point, and the strength of the gravitational field. They had also been taught the definition of a system, potential and kinetic energy, and the transfer of energy into or out of a system, including work.
Details of the sample
The sample consisted of student teachers participating in three different courses.
- 48 non-science majors training to become elementary school teachers.
- 36 engineering majors taking an introductory mechanics course.
- 40 students on a ‘Survey of Physics’ course designed to satisfy a general education requirement.