| We could ask why movement is the first physical phenomenon we study in an introductory course on Physics. The answer is simple: it is one of the most common phenomena which occur around us, even in nature we find movements which are easily observed and truly beautiful .
A rigorous study of any event needs to be described with exactitude. What do we need to observe a movement?
An indispensable instrument for observing and analyzing a movement is one that measures time. You can probably think of several instruments we use for this. We will think of a simple chronometer which will show the passing of time while we make the observations. We also need an exact definition of other concepts: Reference System, trajectory and displacement.
We will introduce them one by one... | 
