Question

an athlete cover one round of a circular track of diameter 200 m in 40 seconds find the distance travelled by him and magnitude of the displacement displacement at the end of 3min 20 second​

Answer 1

radius of this circular path is 200 / 2

= 100 m

It is covered by the athlete in 40 secs.

Thus, the total distance that the athlete moves is the circumference of the circular track.

Circumference of a circle is given by 2pr,

= [2*3.14*100 m] (As p = 3.14 )

= 628 metres.

Now, in 40 secs he can travel 628 metres.

Therefore, in 2 mins 20 secs, distance travelled = ?

2 mins 20 secs = [(2*60) + 20] secs

= 140 secs

Thus in 140 secs he travels a distance of (628 / 40) * 140

= 2198 metres

Now, the displacement is the shortest path from travelled from the initial position to the position at the end of 2 mins 20 secs, or 140 secs.

Now, the athlete completes in 40 secs 1 complete round of the track

Then, in 140 secs, he can complete, [(1/40) * 140) rounds

= 3.5 rounds

Therefore, at the end of 3.5 rounds he will be in a position which is exactly opposite to the starting point in the circular track. Therefore, the shortest path from the initial or starting point to the opposite of it is the diameter of the circular path, that is 200 metres.

Answer 2

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