The auther had tested two groups of students, the junior high school students who had not yet learned the law of inertia, and the undergraduates who had already learned it, in order to examine whether or not, they would be able to understand the phenomena relating to the law of inertia. By applying the factor analytic technique to these tests, several factors were extracted. The purpose of this study was to investigate whether the extracted factors may be accepted from a viewpoint of the natural structure. The tests obtained the affirmative results from the subjects who had learned the law of inertia, but not from the subjects who had not learned it yet.
