Student use of vectors in the context of acceleration

Abstract

A functional understanding of Newton's second law as a vector equation requires that students be able to reason about forces and acceleration as vectors. In this paper, we present data describing students' conceptual difficulties with vector quantities such as acceleration. These data suggest that after traditional instruction in introductory physics, some students do not recognize the vector nature of this quantity. Other students do not have the requisite procedural knowledge to determine acceleration, and are therefore unable to reason qualitatively about Newton's second law. We describe some specific procedural and reasoning difficulties we have observed in students' use of vectors quantities. In addition, we describe instructional difficulties in mechanics that we observed on the basis of our research into student understanding. Some modifications in the instruction were intended to improve students' understanding of the vector nature of acceleration, and to promote student use of vectors when solving mechanics problems. Finally, we describe initial measurements of the effectiveness of these modifications.