An athlete starts from point P on a circular track of circumference 400 m.
(i) After completing one full lap in 80 s, state the athlete’s (a) distance covered, (b) displacement, (c) average speed, and (d) magnitude of average velocity. Give reasons for each answer.
(ii) The athlete now runs exactly half a lap (200 m) from P to the diametrically opposite point Q in 40 s. Compare the average speed with the magnitude of average velocity for this half-lap and justify the difference, if any.