Some students confuse friction and normal reaction, as both arise from an interaction between an object the surface it is sitting on

Forces and Motion


More generally, students may confuse Newton's first and third laws because they do not recognise that the forces in an interaction pair always act on different objects, and confuse the balanced forces on a stationary object (such as a box sitting on the floor) with the equal forces of an interaction pair.



Diagnostic Resources

Resource that Address This

  • Friction

    This resource gives an accessible explanation of friction.

    View Resource
  • Friction between solid surfaces (11-16)

    Source - Practical physics/ Force and motion/ Friction, turning and other effects

    Part 3 explores the idea of normal force.

    View Resource
  • Episode 214: Work done by a force (16-19)

    Source - TAP/ Work, energy and power

    Activity 214-1  explores work done in raising a weight using a ramp.  The explanation included both friction and normal force.

    View Resource


The following studies have documented this misconception:

  • 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

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