Question

An athlete completes one round of a circular track of radius r in 40 s. his displacement at the end of 2 minutes will be :

Answer 1

The athlete will cover a distance of 2*π*R in 40 seconds while his displacement would be zero at that time. Similarly in 80 seconds, the distance covered would be 2*2*π*R and the displacement would be zero at that time.

Therefore, in 140 seconds, the athlete will cover the distance of 140/40=3.5 times 2*π*R=7πR. Since, in 140 seconds the athlete will be on the opposite side of the circle, his displacement would be 2R. This can be understood as in 120 seconds , the athlete will be at the starting point.