Using the position-time and velocity-time graphs we can deduce the properties of the free fall.  We will not only study the case where we let a body fall from rest; we will also take into account whether it has acquired a certain velocity both from ascending and from falling.  

   We will do this experiment for a vacuum, but the results are valid when the friction of the air is negligible; for example when a relatively heavy aerodynamic body falls from a low altitude.