Many students are unable to identify correctly the forces acting on each object in a situation where two or more objects interact

Forces and Motion


This may mean that students commonly struggle to construct accurate free-body diagrams. 

Diagnostic Resources

Resources to Address This

  • Describing interactions

    This resource provides a discussion framework for analysing interactions between objects.

    View Resource
  • Cardboard arrows (5-11 and 11-14)

    Using cardboard arrows to build up force diagrams.

    View Resource


  • Clement, J. () "Students' alternative conceptions in mechanics: a coherent system of preconceptions?" in H. Helm, and J. D. Novak (eds.), Proceedings of the International Seminar: Misconceptions in Science and Mathematics. Cornell University, Ithaca, NY, 310-315.

    This study highlighted common ideas among students, including the ideas that a force can be used up; a force inside a moving object is what keeps it going and if there is motion, there must be a force in the direction of motion. They suggest teachers develop metaphors which organise intuitions the student already has.

    Paper digest

  • diSessa, A. () Unlearning Aristotelian Physics: A Study of Knowledge-Based Learning. Cognitive Science, 6 (1), 37-75.

  • Brown, D. E. () Students' Concept of Force: The Importance of Understanding Newton's Third Law. Physics Education, 24 (6), 353-357.

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