# Many students think of a force as a property of objects, not as something that arises when two objects interact

Forces and Motion

Misconception

Students may think that a moving object has a force within it that keeps it going. It is given this force by whatever pushes or pulls it to get it moving, and when this force is 'used up', the object stops moving.

### Diagnostic Resources

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

• A teapot: not Newton's third law (11-14)

This resource provides advice on how to talk about forces in the classroom.

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• Where we've got to with contact forces (5-11)

This resource summarises identifying forces and how they arise.

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• Stretching and compressing materials (11-16)

Exploring how the forces affect materials.

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## References

The following studies have documented this misconception:

• Trumper, R. and Gorsky, P. () A cross-college age study about physics students' conceptions of force in pre-service training for high school teachers. Physics Education 31 (4) 227-236.

This Israel-based study compares the ability of students to develop their ideas about energy with their open or closed-mindedness along with their level of cognitive operation. It found that students with greater prior knowledge developed ideas more successfully and that there was no correlation with open or closed-mindedness.

Paper digest

• Twigger, D., Byard, M., Driver, R., Draper, S., Hartley, R., Hennessy, S., Mohamed, R., O'Mally, C., O'Shea, T. and Scanlon, E. () The conception of force and motion of students aged between 10 and 15 years: an interview study designed to guide instruction. International Journal of Science Education 16 (2) 215-229.

Students can be very unclear about the difference between energy and force, often believing that they are the same thing. This leads then to the idea that objects slow down because they are ‘using up’ energy, rather than realising that forces are acting to change the motion. This study suggests that careful analysis of motion graphs, coupled with force diagrams can help overcome these issues and that the concept of momentum should be introduced earlier in many courses.

Paper digest

• Bliss, J., Ogborn, J. and Whitelock, D. () Secondary school pupils' commonsense theories of motion. International Journal of Science Education 11 (3) 263-272.

Asking students to analyse images from comic strips, rather than the more common force diagrams used in lessons, can be useful in establishing students' understanding of forces. The approach also helps to identify misconceptions, based on students ‘common sense’ when they give their descriptions. These ideas are often resilient to change and need to be explicitly challenged in teaching and learning activities.

Paper digest

• Halloun, I. A. and Hestenes, D. () Common sense concepts about motion. American Journal of Physics 53 (11) 1056-1065.

Many students incorrectly believe that moving objects must be experiencing a driving force and that a constant force will cause uniform motion rather than acceleration. This research shows that these ideas need to be challenged repeatedly, using a wide range of examples and demonstrations for students to start to move towards scientific descriptions.

Paper digest

• 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 idea 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

• Tao, P. K. and Gunstone, R. F. () The Process of Conceptual Change in Force and Motion during Computer-Supported Physics Instruction. Journal of Research in Science Teaching: The Official Journal of the National Association for Research in Science Teaching 36 (7) 859-882.

It is common for students to confuse the concepts of force and motion, leading the ideas such as a constant resultant force will cause movement at a constant speed or that a motionless object cannot have a force acting on it. This research shows that analysing a wide range of scenarios is required to effectively reduce student misconceptions and that care must be taken when moving between contexts otherwise students may quickly revert to their prior beliefs.

Paper digest

• White, B. Y. () Sources of Difficulty in Understanding Newtonian Dynamics Cognitive Science 7 (1) 41-65.

This study examined the responses of 40 students (mean age 16.4) from an upper-middle-class suburb in the US to a series of questions on Newtonian dynamics. Solutions and any comments made during the questions were recorded, as well as interviews and diagrams drawn.

• Watts, D. M. () A study of schoolchildren's alternative frameworks of the concept of force. International Journal of Science Education 5 (2) 217-230.

This study used an interview approach to identify the conceptions of force in 12 students aged 11-17. Students were drawn from a range of schools in the Greater London area, from both junior science classes and advanced-level physics classes.

• McCloskey, M., Caramazza, A. and Green, B. () Curvilinear Motion in the Absence of External Forces: Naïve Beliefs About the Motion of Objects. Science 210 (4474) 1139-1141.

Many students have misconceptions about the motion of objects, for example, the idea that objects can move in curved paths without external forces acting. This study probed 47 university students' conceptions in different situations (15 with no formal physics education, 22 with high school physics, and 10 with college-level physics).

• Maloney, D. P. () Rule-governed physics: Some novice predictions. International Journal of Science Education 7 (3)

295-306

This US-based study asked a sample of 'college students' to complete a series of tasks designed to test their knowledge of force and motion prior to any instruction. Most of the tasks presented the students with two similar situations and asked them to predict which would exhibit a certain property more strongly (e.g. "Which has higher velocity?")

• Fischbein, E., Stavy, R. and Ma-Naim, H. () The Psychological Structure of Naïve Impetus Conceptions. International Journal of Science Education 11 (1) 71-81.

• Brown, D. and Clement, J. () 'Misconceptions Concerning Newton's Law of Action and Reaction - The Underestimated Importance of the Third Law' in J. D. Novak (ed.), Proceedings of the Second International Seminar: Misconceptions and Educational Strategies in Science and Mathematics (Volume III). Cornell University, Ithaca, NY, 39-53.

• Gilbert, J. K., Watts, D. M. and Osborne, R. J. () Students' Conceptions of Ideas in Mechanics. Physics Education, 17 (2) 62-66.

• Osborne, R. () "Building on Children's Intuitive Ideas" in R. Osborne & P. Freyberg (Eds.), Learning in Science. Heinemann, Auckland, 41-51.

• Ogborn, J. () Understanding students' understandings: An example from dynamics. International Journal of Science Education 7 (2) 141-150.

• Clement, J. () Students' preconceptions in introductory mechanics. American Journal of Physics 50 (1) 66-71.