Question

an athlete completes one round of a circular track of diameter 40m in 5s what will be the distance covered and the displacement at the end of 4 minute's​

Answer 1

Given that,

Diameter D=200m

Radius r=100m

Time, complete one round t=40s

Time in 2 minute 20 second t=2×60+20

We know that,

Circumference of circle =2πr=2×3.14×100=628m

Now, in 40 s athlete cover a distance of 628 m

In 1 s distance covered by the athlete =

40

628

=15.7

In 140 s distance covered by the athlete =15.7×140=2198m

Now, the number of rounds

n=

628

2198

n=3.5

So, in given time of 2 minute 20 second, athlete will complete 3.5 rounds to the circular track

Now, 3.5 rounds means three rounds and half round. This means after the 3.5 rounds athlete will be just opposite to the starting point that means the displacement is equal to the diameter of circular path

Hence, the distance covered is 2198 m and displacement is 200 m