Many students think the resistance of an object to changes in its horizontal motion is due to its weight (rather than its mass)

Forces and Motion


Diagnostic Resources

The following worksheets may help to identify whether students hold this particular misconception.

For more information, see the University of York EPSE website.

Resources to Address This

  • The inertia balance or 'wig-wag' (11-16)

    Source - Practical physics/ Force and motion/ Inertia and Newton's first law

    This resource shows that resistance to motion depends on the mass of the body being accelerated, rather than on its weight.

    View Resource
  • The effects of force and mass on motion (11-16)

    Source - Practical physics/ Force and motion/ Force, mass and acceleration

    Students can quickly see that force and mass have opposite effects on acceleration.

    View Resource


The following studies have documented this misconception:

  • Brown, D. and Clement, J. () "Classroom Teaching Experiments in Mechanics" in R. Duit, F. Goldberg, & H. Niedderer (eds.), Research in physics learning - theoretical issues and empirical studies. San Diego State University, San Diego, CA.


    Review sheet

  • Fischbein, E., Stavy, R. and Ma-Naim, H. () The Psychological Structure of Naïve Impetus Conceptions. International Journal of Science Education, 11 (1),


    Review sheet

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