Analyzing students' skill in drawing a free-body diagram

Abstract

The force concept is one of the important concepts that should be mastered by the student. The most common approach to understand this concept is by using the pictorial representation. The pictorial representation often used is the free-body diagram. Students who can draw the free-body diagram correctly indeed be able to solve the problems well. However, drawing this free-body diagram is still difficult for many students. This study aimed to analyze the students' skill in drawing free-body diagrams and find out the difficulties. There were twenty-two high school students participated in this research study. The instrument used was an essay test consist of four problems. Students were asked to draw a free- body diagram of the objects in each problem. Students' answer was analyzed descriptively. The results of this study showed that the students' ability to draw the free-body diagram was not good enough. The difficulties experienced by students in drawing free-body diagrams were: (1) unable to identify the forces acting on objects; (2) inaccurate in determining the action point of the force; (3) inaccurate in determining the direction of the force vector; and (4) inaccurate in determining the length of the force vector.