Q:  What happens to the decay time if we increase the mass?

          The decay time increases.  Make sense -- a large
          mass is harder to stop than a small one.



  Q:  What happens to the decay time if we increase the
             resistive force?

          The decay time decreases.  Makes sense -- 
          more air resistance should slow the system down quicker.


  Q:  What happens to the decay time if the resistive force disappears?

          The decay time goes to infinity -- meaning that
          the system continues to oscillate forever.