An athlete completes one round of circular track of diameter 200 m in 4 sec. What will be the distance after 2 mins 20 secs and the displacement after 2 mins and 20 sec? (i) 2200 m (ii) 4023 m (iii) 100 m (iv) 200 m
Answers
Explanation:
Diameter of circular track = 200 m
Radius, r = 200/2 = 100 m
Time taken by athlete to complete one round = 40 seconds.
To Find :-
Distance covered = ??
Displacement = ??
Formula to be used :-
Speed = Distance/Time
Circumference of circle = 2πr
Solution :-
2 min 20 seconds = 140 seconds
Number of rounds = 140/4 = 35
⇒ Distance covered = 35 × circumference
⇒ Distance covered = 35 × 2 × 22/7 × 100
⇒ Distance covered = 5 × 2 × 22 × 100
⇒ Distance covered = 22000 m
Hence, the distance covered at the end of 2 min 20 seconds is 22000 m or 22 km.
And displacement is 200 m as it return to initial position again.
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Answer:
The distance covered is 2200 m and the displacement is 200 m.
Explanation:
The diameter of the circular track is given as 200 m. That is, 2r=200 m.
From this radius is calculated as Radius, r = 100 m.
In 40 sec the athlete complete one round. So, in 2 mins and 20 secs, that is, 140 sec the athlete will complete = 140 / 40 = 3.5 (three and a half) rounds.
One round is considered as the circumference of the circular track.
The distance covered in 140 sec = 2πr×3.5=2×3.14×100×3.5=2200 m.
For each complete round the displacement is zero. Therefore for 3 complete rounds, the displacement will be zero.
At the end of his motion, the athlete will be in the diametrically opposite position. That is, displacement = diameter = 200 m.