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

  • Describing interactions

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

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

    Source - SPT/ Mf03TA04 and Fo01TA03)

    Using cardboard arrows to build up force diagrams.

    View Resource


The following studies have documented this misconception:

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


    Review sheet

  • 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.


    Review sheet

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


    Review sheet

Limit Less Campaign

Support our manifesto for change

The IOP wants to support young people to fulfil their potential by doing physics. Please sign the manifesto today so that we can show our politicians there is widespread support for improving equity and inclusion across the education sector.

Sign today