The physical tool for analyzing collision accidents narrows down to the conservation law of momentum. The conservation law of momentum which is also utilized to investigate or to analyze a traffic accident is essential to Newton mechanics. This paper suggests an alternative analytical tool based on the conservation law of momentum. Simply put, the tool is a alternative qualitative method of analyzing a car`s direction to find out whether it is driving over the centerline This paper proposes a deduction theory that use qualitative information to make a qualitative analysis of which car drove over the center line.