A large cubical shaped block of mass M rests on a fixed horizontal surface. Two blocks of mass aod are connected by a light inextensible string passing over a light pulley as shown. Neglect friction everyvhere. Then the constant horizontal force of magnitude F that should be applied to M so that do not move relative to M is:
Let a be the acceleration of cubical block of mass M from ground frame. Then from the frame of block of mass M, forces on are as shown. Hence for to remain at rest in frame of M