Texas Instruments TI-83 Manual Book page 586

7. Press † to move to the path of the ball. Notice the values of
( is unchanged). Notice where the cursor is located. This is the
T
position of the ball when the ferris wheel passenger passes the
intersection. Did the ball or the passenger reach the intersection first?
You can use r to, in effect, take snapshots in time and explore
the relative behavior of two objects in motion.
TI-83 Plus Activities
and
X Y
583