In a free space a rifle on mass `M` shoots a bullet of mass `m` at a stationary block of mass `M` distance `D` away from it . When the bullet has moved through a distance `d` towards the block the centre of mass of the bullet `-` block system is at a distance of `:`

Options

A. `((D-d)m)/(M +m)` from the bullet
B. `(md + MD)/(M + m)` from the block
C. `(2md + MD)/(M + m)`from the block
D. `((D-d)M)/(M + m)` from the bullet

Answer

D

Explanation

Distance between bullet and block at this instant is (D-d)
Distance of CM from bullet = `(M/(M+m))(D-d)`