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 is
distance
(3)

Answer 1

Explanation:

particle completes each circle in 40 sec.

in 2 min 20 sec means 140 sec.

it means it will completes it's three circle in 120 sec and in remaining 20 sec it will cover only half distance of a circle.

so total displacement is for half distance of circle which is equal to 2 R means from upper level to lower level of a circle.

2πR is periphery of a circle

then distance is equals to 2πr+2πr+2πr+πr =7πr

πr is for last half circle.

and displacement is 2R.

ratio of displacement/distance is

2R/7πR

=2/7π

π = 22/7

answer is 1/11.

hope it helps..

you can comment me..if you don't understand.

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