Many pupils 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 pupils 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

IOP DOMAINS Physics CPD programme

The IOP is proud to present our new Forces CPD Domain

This is the first of a collection of videos for you to view ahead of our live support sessions for teachers and coaches of physics.

Find out more