Question

A athletic complete one round of a circular track of radius R in 40 sec . what Will be his displacement at the end of 2 minute 20 second.?

Answer 1

Every 40 seconds he comes back to original position l. So in 140 s he would cover 3 and half circles. Hence

Total distance is 2r pi x 3.5 = 7r pi.

Total displacement will be = 2r since ball will be directly across the diameter .

Answer 2

the displacement will be
$\pi {r}^{2} \div 2$
the half of the circumference will be the displacement.


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