Question

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

Answer 1

An athlete completes one round of a circular track of diameter 200 m in 40 s. What will be the distance covered and the displacement at the end of 2 minutes 20 s?

Answer :
Given, Total time = 2 minutes 20 seconds
= 2 × 60 + 20
= 120 + 20
= 140 seconds
As in 40 s,
The number of rounds completed = 1
Now we have to find the number of rounds completed in 140 seconds:
So, In 140 s, the number of rounds completed =× 140
= 3.5

(a) Diameter of circular track = 200m
Radius of circular track, (r) = 100m
Now, Distance covered in 1 round = Circumference of the circular track
= 2πr
= 2 × × 100 m
= 628.57 m
And,
Distance covered = 628.57 × 3.5 m
So, in 3.5 rounds the total distance covered = 2200 m
(b) As the athlete makes 3.5 rounds of the circular track and if he starts from point A then after completing the 3 rounds he will be at the same point A. On starting again from the same point and makes the remaining half round he will reach at the point B. Therefore, the displacement of the athlete will be equal to the diameter of the track i.e., 200m.

Answer 2

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