Students generally have difficulty understanding friction and its associated phenomena. High school and introductory college-level physics courses usually do not give the topic the attention it deserves. We have designed a sequence for teaching about friction between solids based on a didactic reconstruction of the relevant physics, as well as research findings about student conceptions. The sequence begins with demonstrations that illustrate different types of friction. Experiments are subsequently performed to motivate students to obtain quantitative relations in the form of phenomenological laws. mechanisms producing friction. Concerning the mechanisms producing friction we stress that there are a variety of phenomena, the relevance of which varies according to the situations and materials considered. A number of mechanisms are presented in a descriptive and intuitive form. To help students understand the mechanisms producing friction, models illustrating the processes taking place on the surface of bodies in contact are proposed. Some historical explanatory models are considered: Bélidor’s model of spherical asperities, Coulomb’s model of interlocking asperities and the Bowden and Tabor model of adhesive junctions. We contrast these older models to more recent ones, such spring-like models and atomic interaction models based on computer simulation. Although partial and limited in applicability, these models have the advantage of presenting visual representations of meso–micro-asperities in interaction. Testing of the sequence with student teachers and with high school students has provided encouraging results, both from the point of view of overcoming some of the typical difficulties that emerge in the physics education literature, and from the perspective of stimulating new and richer approaches and lines of reasoning in relation to physical situations connected with friction.

How to teach friction: Experiments and models

BESSON, UGO;BORGHI, LIDIA;DE AMBROSIS VIGNA, ANNA;MASCHERETTI, PAOLO
2007

Abstract

Students generally have difficulty understanding friction and its associated phenomena. High school and introductory college-level physics courses usually do not give the topic the attention it deserves. We have designed a sequence for teaching about friction between solids based on a didactic reconstruction of the relevant physics, as well as research findings about student conceptions. The sequence begins with demonstrations that illustrate different types of friction. Experiments are subsequently performed to motivate students to obtain quantitative relations in the form of phenomenological laws. mechanisms producing friction. Concerning the mechanisms producing friction we stress that there are a variety of phenomena, the relevance of which varies according to the situations and materials considered. A number of mechanisms are presented in a descriptive and intuitive form. To help students understand the mechanisms producing friction, models illustrating the processes taking place on the surface of bodies in contact are proposed. Some historical explanatory models are considered: Bélidor’s model of spherical asperities, Coulomb’s model of interlocking asperities and the Bowden and Tabor model of adhesive junctions. We contrast these older models to more recent ones, such spring-like models and atomic interaction models based on computer simulation. Although partial and limited in applicability, these models have the advantage of presenting visual representations of meso–micro-asperities in interaction. Testing of the sequence with student teachers and with high school students has provided encouraging results, both from the point of view of overcoming some of the typical difficulties that emerge in the physics education literature, and from the perspective of stimulating new and richer approaches and lines of reasoning in relation to physical situations connected with friction.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/104532
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