Question

a particle is moving along a circle such that it completes one revolution in 40 seconds.In 2 minutes 20 seconds,the ratio |Displacement|/Distance is

Answer 1

Pls ignore the image,
distance = 140/40 × 2πr = 3.5 × 2πr
displacement= 2r
displacement/distance= 1/3.5π
= 1/11 .

here you go. :) hope I was helpful.

Answer 2

$\text{Let the radius be r}\\Time = (2 \times 60) + 20 = 140\ s\\Distance \ covered (1. revolution)= 2\pi r \\Time (1 \ revolution) = 40s\\\\ Revolutions\ completed \ in \ 140s = \frac{140}{40}\\Then, Distance\ covered \ in \ 3.5 \ revolutions = (3.5 \times 2\pi r) m = 7\pi r\ m\\Then,Displacement\ in \ 3.5 \ revolutions = 2r \ m\\\therefore \frac{Displacement}{Distance} = \frac{2r}{7\pi r} = \frac{2}{7\pi} = \frac{1}{11}$