The word trajectory derives from the French “trajectoire” meaning “line described in space by a moving body, and, more commonly, the one followed by a projectile”. The word trajectory has different types of uses depending on the context to be treated, as in kinematics the trajectory is a space of the geometry of the following postures through which a body passes in its displacement that will depend on each reference in which displacement is explained.

The classical mechanical trajectory resembles the following geometric sites that a body inhabits while moving and its specification depends on the site where the observation is made.

The trajectory of a particle in space that is established by the position vector “R” that is traced at the origin “O” of a referential xyz to the position of the particle “P”. When the molecule moves, the limit of the line “R” describes a curve “C” in space, which is called the trajectory.

The curvilinear trajectory can be two-dimensional because it has two dimensions that are “wide and long”, this is a flat and physical launching piece of the universe that is used more than anything in three-dimensionality that has three dimensions that are “width, length and depth.

The erratic trajectory is when the displacement is essential, but also its geometric shape is very irregular that it is outside the rule or norm, contrary to them.