Question 74028
You need a two-dimensional graph.  The number line could only 
show you a range of values, which may be all you want. You
could then graph the length between a(minimum) and b(maximum)
but not the movement. The movement in time could be shown with
a horazontal time axis and length vertical axis. It would be 
like a sine curve over a fixed length of time.
Cheers,
Stan H.