## Many pupils do not see forces as arising from an interaction between two objects.

Forces and Motion

Misconception

Many pupils do not see forces as arising from (and during) an interaction between two objects, and always as pairs of equal forces, acting on each of the interacting objects.

### Diagnostic Resources

• Describing interactions (14-16)

Source - SPT/ Fmo4TA04

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

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• Selecting and developing activities for finding forces (5-11)

Source - SPT/ Mf03TA01

Based on the Physics Narrative and the Teaching and Learning Issues, to find appropriate activities.

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• Looking through forces spectacles (11-14)

Source - SPT/ Fo01TA04

The purpose of this activity is for pupils to make simplified drawings of each of the stations in the circus and to draw in the forces acting on the different objects.

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• Episode 202: Forces in equilibrium (16-19)

Source - TAP/Mechanics/ Statics

In this episode, students will learn about the conditions for static equilibrium (excluding moments of forces).

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## References

The following studies have documented this misconception:

• Gunstone, R. F. and White, R. T. () Understanding of Gravity. Science Education, 65 (3),

291-299.

This study presented a sample of first year physics undergraduates at Monash University, Australia, with eight physical situations. The students were asked to make predictions as to what would happen if a certain action was taken. The action was then taken, and the subjects were asked to explain any discrepancies between their prediction and the result.
Review sheet

• Minstrell, J. () Explaining the "At Rest" Condition of an Object. The Physics Teacher, 20 (1),

10-14.

This study examined the explanations given by two classes of high school students in an economically affluent suburb of Seattle for objects at rest. Students were asked to diagram and defend the forces involves in a series of examples including (i) book at rest on a table, (ii) book held by hand, (iii) multiple books held by hand, (iv) book hanging from a spring, (v) book at rest on a table which is shown to depress, (vi) book at rest on a table again. Recordings of student discussions were made, and homework papers, as well as pre- and post-instruction test results were examined.
Review sheet

• Clement, J. () Using Bridging Analogies and Anchoring Intuitions to Deal with Students' Preconceptions in Physics. Journal of Research in Science Teaching, 30 (10),

1241-1257.

This study aimed to measure the effect of using 'bridging' analogies (analogies with intermediate examples) to address the preconceptions of high school physics students. The sample consisted of 3 experimental groups across 2 schools (comprising 150 students) and 2 control groups across 2 schools (comprising 55 students). Data was collected using pre- and post-intervention tests, and was analysed using a t-test.
Review sheet

• Terry, C.; Jones, G. and Hurford, W. () Children's Conceptual Understanding of Forces and Equilibrium. Physics Education, 20 (4),

162-165.

https://iopscience.iop.org/article/10.1088/0031-9120/20/4/306/pdf
• Brown, D. E. () Students' Concept of Force: The Importance of Understanding Newton's Third Law. Physics Education, 24 (6),

353-357.

https://iopscience.iop.org/article/10.1088/0031-9120/24/6/007/pdf