Question

An athlete completes one round of a circular track of diameter 200m in 40s what will be the distance covered and the displacement at the end of 2 min and20s

Answer 1

Heya...

HERE IS THE ANSWER

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

Time of one rotation = 40s

Time after 2m 20s = 2 x 60s + 20s = 140s

Distance after 140 s = ? 

Displacement after 140s =?

We know that, velocity along a circular path =Circumference/time

⇒v=2πr/40s

⇒v=2×3.14×100m/40s

⇒v=628m/40s

⇒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,rotating in 40 s=1

Therefore, rotation in 1s =(1/40)

∴rotation in 140s=1/40×140=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

HOPE IT HELPS YOU

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Answer 2

Answer:

Given :-

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.