Qualitative Physics based on exact physical principles*t

Consider a two-body collision process . Raiman[1986] observed that the conventional qualitative approach to this problem amounts to suppressing the mass information, which becomes inadequate when one wants to determine the direction of the velocity of an abject after a collision . He resolved this by going back to the original algebraic equations, which have all the mass factors . He then proceeded with order of magnitude reasoning . There is at least one weal: point in Ralman's approach, i .e . intuitively the direction of concerned should be associated with some threshold phenomena . But thresholds are absent in his work . Consequently, he is only able to predict the direction in the region substantially beyond the expected threshold . Our general point of view is that, physical phenomena which we encounter daily are governed by a number of relatively simple physical principles . It is often possible to define a physical system or a process in terms of a collection of intuitive and yet exact statements . Complexities anise when we try to see how different relationships work together . We believe that Raiman's semiquantitative approach is a step in the right direction . However, for those problems wluch can be solved algebraically, we would like to go one step further to work with the exact equations and