Student performance on drawing free body diagrams and the effect on problem solving

Abstract

Using data involving free-body diagrams on final exams from a first year Mechanics I course, a broadly defined rubric was created which assesses free body diagrams in six separate categories: overall quality, forces/moments, body, axes, dimensions, and resulting equations. Data from 238 free-body diagrams and equilibrium equations were then assessed. Results of the study found that 45% of the equilibrium equations had errors in them of which 67% of those errors were a direct result of errors from the free-body diagrams. Quantitative data on frequency and types of errors found in students' free-body diagrams are provided and discussed.