**ERIC Number:**EJ887939

**Record Type:**Journal

**Publication Date:**2010-Apr

**Pages:**4

**Abstractor:**As Provided

**Reference Count:**0

**ISBN:**N/A

**ISSN:**ISSN-0031-921X

The Role of Sign in Students' Modeling of Scalar Equations

Hayes, Kate; Wittmann, Michael C.

Physics Teacher, v48 n4 p246-249 Apr 2010

Helping students set up equations is one of the major goals of teaching a course in physics that contains elements of problem solving. Students must take the stories we present, interpret them, and turn them into physics; from there, they must turn that physical, idealized story into mathematics. How they do so and what problems lie along the way are a major source of difficulty for us as instructors. In this paper, we consider just one such difficulty, getting the plus and minus signs correct when setting a net force equal to mass times acceleration. Even in such simple equations, we find that students make common errors in how they connect the mathematics and the physics. Specifically, we have seen college physics students use physical and mathematical reasoning inconsistently when determining signs of terms in equations. The problem seems to lie in how a vector equation gets interpreted into a scalar equation (whose form depends on one's choice of coordinate system).

Descriptors: Physics, Equations (Mathematics), Models, Problem Solving, Educational Objectives, Scientific Concepts, Science Instruction, Science Education, College Science, College Students, Teaching Methods, Mathematical Concepts, Mathematics Skills

American Association of Physics Teachers. One Physics Ellipse, College Park, MD 20740. Tel: 301-209-3300; Fax: 301-209-0845; e-mail: pubs@aapt.org; Web site: http://scitation.aip.org/tpt

**Publication Type:**Journal Articles; Reports - Descriptive

**Education Level:**Higher Education; Postsecondary Education

**Audience:**N/A

**Language:**English

**Sponsor:**N/A

**Authoring Institution:**N/A