Four identical bodies each of mass 1 kg are placed touching to each other with centres on a straight line. If their centres are marked A, B, C and D respectively, then the distance of centre of mass of the system from B will be

Options

A. `(AB+BC+BC+CD)/(4)`
B. `(AB+BC+BD)/(4)`
C. `AB+(AC)/(4)+AD`
D. `(AB+BC+CD)/(4)`

Answer

B

Explanation

`R_(g)=(m_(1)x_(1)+m_(2)x_(2)+m_(3)x_(3)+m_(4)x_(4))/(m_(1)+m_(2)+m_(3)+m_(4))`
`m_(1)=m_(2)=m_(3)=m_(4)=m`
`R=((x_(1)+x_(2)+x_(3)+x_(4)))/(4)`
`= (AB+BC+BD)/(4)`