Question

A cyclist moving on circular track of radius 50metres completes one revolution in 4 min .what is his average speed and average velocity

Answer 1

Radius = 50 cm = 0.5 m
time = 4 min = 240 s

Average speed = total distance travelled/ total time taken
  Avg speed = 2πrt = 0.01 m/sAvg velocity = displacement / total time taken = 0Aas initial and final points are same.

Answer 2

given,
r=50
circumference=2*22/7*50
=314.28
t=4min=240sec
average speed=314.28/240
=1.3m/s
average velocity=0(as displacement=0)
average velocity=0