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 minutes 20s
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Answer 1

Answer:

Soln:    Diameter of a circular track (d) = 200m

Time taken to complete one round of track = 40s

Hence,no. of rounds (n) completed by athlete in 1 min. 50 s ,i.e., in 110 s

                           n = 140 s/40s = 70/20 = 35/10 =7/2

i) Distance covered in 1 round is equal to the circumference of the circle , i.e.,

                             2 $\pi$ r = $\pi$d

Distance covered in 2 min. 20 s.

                              s = n.$\pi$d

                                 =7/2 × 22/7  × 200 m

                                 = 2200 m

Hence , distance covered by an athlete in 2 min. 20 s will be 2200 m .

                                         

Answer 2

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.

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