Question

An athlete completes one round of a circular track of diameter 200 m in 40 s. What will be the distance covered and the displacement at the end of 2 minutes 20 s?
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Answer 1

Answer :

Given -

• Diameter of the circular track = 200 m
• Time taken to complete one round = 40 s

To Find -

• Displacement in 2 min 20 s
• Distance in 2 min 20 s

Solution -

2 min 20 s

⇒ 2*60 + 20 s

⇒ 120 + 20 s

⇒ 140 s

Rounds taken = 140/40 = 3.5 rounds

Hence, Distance travelled in 140 s = 2*22/7*100*3.5 = 2200 m.

After 3.5 rounds, the final position will be diametrically opposite to initial position.

Displacement in 140 s = 200 m.

Final Answers :

• Distance travelled in 140 s = 2200 m.
• Displacement = 200 m.

Answer 2

Answer:

Explanation:

Solution,

Here, we have

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 = ??

2 min 20 seconds = 140 seconds

Number of rounds = 140/4 = 35

Here, We know that

Circumference of circle = 2πr

So, putting all the values, we get

⇒ 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.