A runner completes different fractions of a circular track of radius 70 m, starting each time from the eastern end of the track and moving anticlockwise.
(a) Find the distance covered and the magnitude of displacement after the runner finishes exactly half a lap.
(b) Repeat part (a) for one full lap.
(c) Repeat part (a) for one and a half laps.
(d) Comment on how the ratio of distance to displacement changes in the three cases.