an athlete completes one round of a circular track of diameter 200 m in 40 seconds (1) the distance travelled by him at the end of 3 minutes 20 second (2)
the magnitude of the displacement at the end of 3 minute 20 second
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.
Answer:
Diameter of circular track is 200 m so radius is 100 m than the time is 40 sec and the athlete complete this in 2πr because it is a circle and we know that formula than in 80 sec it will be 2πr and in 120 sec it also again 2πr and in 140 sec it will be πr because in 160 sec an athlete complete one rounds so in 120 it will be πr only than we add all and we find 7πr than we calculate this 7×22÷7×100 than the distance will be 2200 m and the displacement will be 200 metre because it complete half round and the diameter is 200 m