Q: An athlete completes one round of a circular track of radius R in 40 s. What will be his displacement at the end of 2 min 20 s ?
Sol. The time = 2 min 20 s = 140 s
In 40 seconds athlete completes = 1 round
In 140 seconds athlete will completes
=140/40 round=3.5 rounds
The displacement in 3 rounds = 0
So net displacement = 2R.