1. Answer the following questions
A) A runner is running a circular path of 400m in 20s. what will be the magnitude of the displacement of the runner in 2 minute 20 seconds ? find the distance traveled.
B) A boy from a moves long is boundary of the field and reaches 'D' in 20s. find its displacement and distance?
Answers
Answer:
1)
Given parameters
The diameter of the circular track = 200 m
Radius (r) = 200/2
r = 100 m
Time is taken by an athlete to complete one round = 40 seconds.
Displacement = ??
Speed = Distance/Time
Total time athlete moves – 2 min 20 seconds
2 min 20 seconds = 2 × 60 + 20
2 min 20 seconds = 140 seconds
Need to find the distance covered in one round
Distance covered in one round = Circumference of circle
Distance covered in one round = 2πr
Distance covered in one round = 2
Distance covered in one round = 2 × 100π
Distance covered in one round =200π
Time is taken by an athlete to complete one round = 40 seconds.
Number of rounds completed in 140s = 140/40
Number of rounds completed in 140s = 35
Distance covered = 3.5 × circumference
Distance covered = 3.5 × 2πr
Distance covered = 3.5 × 2 × 3.14 × 100
Distance covered = 2200 m
Hence, the distance covered at the end of 2 min 20 seconds is 2200 m or 22 km.
And displacement is 200 m as it returns to the initial position.
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