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

we know that T=2min+20 Second=140 seconds


as 2πR distance is covered in 40 seconds

then in 140 seconds total distance covered =


2πR×140/40= 7πR = 3(2πR)+πR

it means athlete completes 3 circle and one half circle ......

so , it is obvious that the athlete is at other end from his starting point..that is the net displacement is Diameter .


then displacement= 2R