A car runs at a constant speed on a circular track of radius $$100\,m,$$  taking $$62.8\,s$$  for every circular lap. The average velocity and average speed for each circular lap respectively is

Solution :
Concept
Average velocity is defined as the ratio of displacement to time taken while the average speed of a particle in a given interval of time is defined as the ratio of distance travelled to the time taken.
On a circular path in completing one turn, the distance travelled is $$2\pi r$$  while displacement is zero.
Hence, $${\text{average velocity}} = \frac{{{\text{displacement}}}}{{{\text{Time - interval}}}}$$
$$ = \frac{0}{t} = 0$$
$$\eqalign{ & {\text{Average speed}} = \frac{{{\text{Distance}}}}{{{\text{Time - interval}}}} \cr & = \frac{{2\pi r}}{t} = \frac{{2 \times 3.14 \times 100}}{{62.8}} \cr & = 10\,m{s^{ - 1}} \cr} $$
NOTE
If a particle moves in a straight line without change in direction, the magnitude of displacement is equal to the distance travelled otherwise it is always less than it. Thus, displacement $$ \leqslant $$ distance.