This thesis contributes an answer to the question whether lacking knowledge of physical facts is sometimes probably only lacking knowledge of appropriate terminology. The main subject of this thesis is an empirical analysis of the term "force" (N = 511 test persons). It tries to separate the influence of terminology from the solution of physical problems. Therefore two ways of investigation were chosen. Firstly, a questionnaire divided into two parts was developed. In the first part the test persons were asked to make non-verbal predictions for observable physical facts which were presented pictorially. In contrast with usual investigations of student`s force concepts, the way of questioning deliberately omittet physical terminology. The second part focused the term "force" as usual. Secondly, students who had learnt different terms for the same physical facts were asked. The results of both investigations show that many of the test persons cannot describe a certain situation by the use of the term "force", though they definitely understand the situation and predict rightly place and velocity.