An athlete completes one round of a circular track of diameter 200 m in 40 s. If he continues to run, what will be the distance covered and the displacement at the end of 2 minutes 20 s respectively ? (1) 2200m , 200m (2) 2200m, 0m (3) 4400m, 400m (4) 2200m, 400m

Answer: (1)

Given

Diameter (d) = 200 m

Radius (r) = 100 m

Displacement is defined as the shortest distance possible between the initial position and the final position.

Since the athlete moves in circular motion displacement is zero because initial and final positions are the same.

Distance covered in 1 round = Circumference of the circle

Circumference of the circle = 2πr

where π = 22/7

The athlete completes one round in the 40s.

Distance covered in 40 sec, i.e in one round = 2 × (22/7) × 100

Distance covered in 40 sec = 628.57m……………..(1)

Distance covered in 1 sec = x m…………………….(2)

Cross multiplication of (1) and (2) gives the value of x.

x = 15.71 m

Distance covered in 2min 20 sec 0r 140 sec = 15.71 × 140

Distance covered in 2min 20 sec = 2199.4 m

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