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Matter In Our Surroundings
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?
Diameter of circular track (D) = 200 m
Radius of circular track (r) = 200/2=100 m
Time taken by the athlete for one round (t) = 40 s
Distance covered by athlete in one round (s) = 2π r
= 2 × ( 22 / 7 )×100
Speed of the athlete (v) = Distance / Time
= (2 × 2200)/(7 × 40)
= 4400 / 7 × 40
∴ Distance covered in 2 minutes 20
seconds (s) or 140 s
= Speed (s) × Time(t)
= 4400 / (7 × 40) × (2×60 + 20)
= 4400 /( 7 × 40) × 140
= 4400 × 140 /7 × 40
=2200 m
Number of round in 40 s =1 round
Number of round in 140 s =140/40
=3.5 rounds
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