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. `(AB+AC)/(2)`
B. `(AB+BC)/(2)`
C. `(AC-AB)/(3)`
D. `(AB+AC)/(3)`

Answer

D

Explanation

`x_(cm)=((x_(1)+x_(2)+x_(3))m)/(m+m+m)`
`= (x_(1)+x_(2)+x_(3))/(3)`
`= (0+AB+AC)/(2)`.