Pedagogical Use of Relativistic Mass at Better Visualization of Special Relativity

Relativistic mass is not incorrect. The main argument against it is that it does not tell us anything more than the relativistic energy tells us. In this paper it is shown that this is not true, because new aspects of special relativity (SR) can be presented. One reason for this definition is to show a relation between time dilation and relativistic mass. This relation can be further used to present a connection between space-time and matter more clearly, and to show that space-time does not exist without matter. This means even a simpler presentation than is shown with Einstein's general covariance. Therefore, this opposes that SR is only a theory of space-time geometry, but it needs also rest mass. Phenomenon of increasing of relativistic mass with speed can be used for a gradual transition from Newtonian mechanics to SR. It also shows how relativistic energy can have properties of matter. The postulates, which are used for the definition of SR, are therefore still clearer and the whole derivation of the Lorentz transformation is clearer. Such derivation also gives a more realistic example for the confirmation of Duff's claims.