A man of mass `80 kg` stands on a plank of mass `40 kg`. The plank is lying on a smooth horizontal floor. Initianlly both are at rest. The man starts walking on the plank towards north and stops after moving a distance of `6 m` on the plank. Then

Options

A. The centre of mass of plank-man system remains stationary
B. The plank will slide to the north by a dsitance `4m`
C. The plank will slide to the south by a distance `4 m`
D. The plank will slide to the south by a distance `12 m`

Answer

(AC)

Explanation

Let x be the displacement of the plank.
Since CM of the system remains stationary
so `80 (6 - x) = 40 x rArr 12 - 2x = x rArr x = 4m`