Question

An athlete completes one round of a circular track of diameter 200 m in 4 s. What will be the distance cover and the displacement at the end of 2 minutes 20 s?​

Answer 1

Answer:

Explanation:

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 Zero as it return to initial position again.

Answer 2

Answer:

Distance = 22 km

Displacement = 0 km

Explanation:

Given:

• Diameter of the circular track = 200 metres

• Time taken to complete one round of the circular track = 4 seconds

To find:

• Distance at then of 2 minutes 20 seconds
• Displacement at the end of 2 minutes 20 seconds

Distance:

Radius of circle = 100 m

2 minutes 20 seconds = $2 \times 60 +20 = 140 \ seconds$

Number of round completed = $\frac{140}{4} = 35 \ rounds$

Distance = 35×Circumference of the circle

Distance = $35 \times 2 \times \pi r$

Distance =$70 \times \frac{22}{7} \times 100$

Distance =22,000 metres

The distance covered is equal to 22,000 metres or 22 km

Displacement:

At the end of 35 rounds the athlete will reach back to the initial position and so the displacement will be 0

Displacement = 0 km