Question

An athletev completes one round of a circular track of diameter 200m in 40 as what will be the distance covered and displacement at the end of 2 minutes 20 seconds

Answer 1

Here we have, Diameter = 200 m, therefore, radius = 200m/2 = 100 m

Time of one rotation = 40s
Time after 2m20s = 2 x 60s + 20s = 140s
Distance after 140 s = ? 
Displacement after 140s =?

We know that, velocity along a circular path =Circumferencetime

⇒v=2πr40s

⇒v=2×3.14×100m40s

⇒v=628m40s

⇒v=15.7m/s

(a) Distance after 140s

We know that,distance=velocity ×time

⇒ distance=15.7m/s ×140 s = 2198 m

(b) Displacement after 2 m 20 s i.e. in 140 s

Since,rotatin in 40 s=1

Therefore, rotation in 1s=140

∴ rotation in 140s=140×140=3.5

Therefore, in 3.5 rotations athlete will be just at the opposite side of the circular track, i.e. at a distance equal to the diameter of the circular track which is equal to 200 m.

Therefore, Distance covered in 2 m 20 s = 2198 m

And, displacement after 2 m 20 s = 200m