Question

an athlete completes one round of a circular track of diameter 200m in 40 s what will be the distance covered and the displacement at the end of 2 minute 20 seconds

Answer 1

hey dear..

the distance covered in one complete round = 40 sec.

 so, circumference of circle of diameter 200 m

  =  π 200  meters.

Distance covered in 2 minutes, 20 seconds or 140 sec: =  200 π  140/40 = 700 π meters

In 140 seconds, the athlete makes 3 complete rounds and runs for 20 secs after that.

in 40 secs, he runs a complete circle (covers 360°).  So in 20 secs, athlete runs half-circle and covers 180°.

So at the end of 140 seconds, athlete is at the diametrically opposite end on the circular track.  

The displacement = vector joining the initial position to the final position.

 It magnitude = diameter = 200 meters.

hope it helps..