engleski

Influence of two different methods for solving freebody diagrams on students' ability to identify forces and apply Newton's law

In most physics courses vector calculus is carried out by resolving the forces into components and then summing up the components of the same direction. Although this procedure facilitates the calculation, it potentially leads to the misconception that the components are also some real forces. In addition, the procedure is not entirely in accord with the concepts of the Newton’s laws which state that the motion of the body is determined by the vector sum of the forces. The question arises: is the direct vector method or application of the polygon rule for vector addition more successful in teaching mechanics? In this study, we have developed an instrument to measure students’ ability to identify real forces in different diagrams. Using this instrument we made an initial study of the effectiveness of the two different problem solving methods. Our test, consisting of 12 items, was administered to two groups of first-year physics students at Rijeka (RG) (n = 27) and Split (SG) (n = 25) university, after the “concept of force” had been covered in class. Afterwards, both groups exercised additional force diagrams tasks for a period of two class hours. The only difference was that RG used the polygon rule and SG the vector components method. Post test showed a shift in the average rate of correct responses which was significantly larger for RG. Based on these initial results we formulate the working hypothesis for the future investigation: If we apply the teaching method where the force diagrams are solved by using the polygon rule, we foster the students' ability to identify real forces and we improve their understanding of Newton's laws.

force diagrams

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