Q17 of 47 Page 8

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?

Given, Total time = 2 minutes 20 seconds

= 2 × 60 + 20  (As 1 Minute= 60 Seconds)

= 120 + 20

= 140 seconds

According to Question,

In 40 Seconds⇒ 1 Round is completed
∴In 140 Seconds⇒



(a) Calculation of Distance Covered in 3.5 Rounds
Diameter of circular track = 200m (Given)

∴Radius of circular track, (r) = 100m( Diameter/2)

Now, Distance covered in 1 round = Circumference of the circular track

= 2πr

=

= 628.57 m
∴ Distance covered in 3.5 Rounds = 628.57 X 3.5= 2200 m

(b) As the athlete makes 3.5 rounds of the circular track, Suppose 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(Point A)  and makes the remaining half round then 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.

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