An athelete completes one round of a circular track of diameter 200m in 40 sec . What will be the distance and displacement at the end of 2 min 20 sec ?
Answers
Answer: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.
Hence, the distance covered is 2200 m and the displacement is 200 m.
At the end of 2 min and 20 sec, athlete would have taken 3.5 round of the circle.
So distance= 3πd + πd/2
=7πd/2= 7*π*200/2= 700π m
Displacement = diameter= 200 m