Question

An athlete completes one round of a circular track of radius R in 40 sec. What will be his displacement at the end of 2 min 20 seconds?

Answer 1

Total time duration in consideration : 2 min 40 secs = 160 secs

No of complete rounds in this time = 160/40 = 4 rounds

Therefore he will be exactly at the point where he started. Hence his displacement will be 0, although he will cover a distance of 4 (2πR)

Answer 2

2 min 20 second = 140 second.
he completed one round in 40 second.
in 140 second, he will cover= 140/40=3.5 round.
after 3.5 round, he would be on the opposite side of the starting point.
So the displacement will be the diameter or 2R.