Interaction and force in Newton's 3rd law an inventory of secondary school students' beliefs

النوع : Mémoire

Interaction between physical objects is a generic notion in physics, and force is the most commonly used concept for representing all forms of interaction in secondary-school physics. Students’ understanding of interaction and force is thus a main concern in secondary-school physics courses. In this thesis we report on the development of a paper-and-pencil instrument for ascertaining student beliefs about interaction among physical objects, and the ways interaction is represented with the concept of force within the context of Newtonian theory of mechanics and mainly Newton’s third law. Results show that participating secondary school students have wrong beliefs about interaction and force, and the way they are related. Many students believe that an object can interact with itself, and they do not see the necessity of an object-agent pair for interaction. They consider force and interaction as being completely independent, and they fail to realize that force is one invented concept among many to represent interaction. Instead of realizing that a force represents an interaction between two objects, some students believe that force is a by-product of interaction: one object produces a force by itself and then imparts this force on another object. Other students believe that objects producing forces should be alive (living or in motion). Other wrong beliefs mainly associated with the motion of objects are detected. Many students believe that motion is always maintained by a specific agent, and they do not usually apply Newton’s 2nd law to real world situations. They also fail to understand Newton’s 4th law; they compose forces acting on different objects, and they believe that one agent can produce two forces on the same object especially in cases where, in physics, a force is split into two components. Outcomes are discussed with their implications to teaching Newtonian mechanics and future research.