Momentum Vector Diagrams

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Collisions are real-world situations from everyday life (such as car crashes, playing billiards, etc.) that can be described and understood by the principle of conservation of momentum. One might expect that learning from simple collisions might help students understand more complicated physical phenomena. However, from our teaching experiences we often find that even in a physics problem involving a simple physics collision, students have trouble arriving at the correct answer. Multiple representations are tools to help students think and act like physicists when solving problems. Examples of these representations are motion diagrams, free-body diagrams, energy bar charts, impulse-momentum bar charts, and impulse-momentum diagrams. Impulse-momentum diagrams were designed to help students understand the principle of conservation of momentum. They effectively show the magnitude of the momentum but are limited to only problems in one dimension. In this paper we will show a structured teaching method using momentum vector diagrams (MVD) as a tool. The MVD method is developed to help students understand the principle of conservation of momentum and vector property of momentum, and to be able to use it to solve collision problems especially in two dimensions.