Three identicle particle each of mass `1 kg` are placed with their centres on a straight line. Their centres are marked `A, B and C` respectively. The distance of centre of mass of the system from `A` is.

Options

A. `(PQ + PR +QR)/(3)`
B. `(PQ + PR)/3`
C. `(PQ + QR)/3`
D. None of the above

Answer

B

Explanation

`X_(CM)` (from P) `=(m xx O +m xx PQ + m xx PR)/(m+m+m)` (m = 1kg)

or `X_(CM) = (PQ + PR)/3`