A block of mass M is placed on the top of a bigger block of mass 10 M as shown in figure . All the surfaces are frictionless. The system is released from rest. Find the distance moved by the bigger block at the instant the smaller block reaches the ground.
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Explanation

If the bigger block moves towards right by a distance X , the smaller block will move towards left by a distance (2.2 m - X) . Taking the two blocks together as the system , there is no horizontal extrnal force on it . The centre of mass, which was at rest initially , will remain at the same horizontal position .
Thus , `M(2.2 m-X) = 10 "MX" (or)`
2.2 m = 11 X or X = 0.2 m