an athlete completes a circular track of diameter 200m in 20 sec .calculate the distance travelled by him and the magnitude of the displacement of the athlete at the end of 1 m and 10 seconds?

Dear Student,
Please find below the solution to the asked query:

since the athlete completes one round in 20s. Therefore,
number ofrounds made in 1 min 10 sec or 70 s = 70/20 = 3.5

Now, 
distance travelled in one round = πd
distance travelled in one round = 200π

distance travelled in 1m 10 s = 3.5×200π
distance travelled in 1m 10 s = 700π = 2200 m

Now, 

displacement at the end of 1 min 10 s= diameter of the circle (since after each round the athlete will be at the start position hence its displacement after each round will be 0, and the displacement in half the round will be equal to teh diameter of the cirlce)

displacement at the end of 1 min 10 s = 100m

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Satyendra Singh