Joe drops a ball from H = 5 m.  How long does it take to fall to the ground?

  The ball accelerates due to gravity at a constant rate of

             a  =  - 9.8 m/s^2


  Using the equations of 1-D kinematics, we can write its position as
  a function of time as

             y(t)  =  H  +  0.5 * a * t^2


  If we set the final position y = 0 m, then we can find the time like so:


              0 m  =  5 m  +  0.5 * a * t^2

             -5 m  =       +  0.5 * a * t^2

            -10 m  =            (-9.8 m/s^2) * t^2


                                10 m
                t  =  sqrt ( --------- )  =  1.01 s
                             9.8 m/s^2