Centre Of Mass Motion

As stated in NCERT Class 11, Chapter 7 (System of Particles and Rotational Motion), the centre of mass of a system moves only under the influence of the net external force, according to the relation F_ext = M a_cm, where M is the total mass and a_cm is the acceleration of the centre of mass. The forces driving the explosion are entirely internal forces acting between the fragments, and by Newton's third law these occur in equal and opposite pairs that cancel. Internal forces therefore cannot change the motion of the centre of mass. Since the bomb was initially at rest and no external force acts on it in deep space, the centre of mass must remain at rest even as the individual fragments scatter in all directions. The option about moving toward the largest fragment is wrong because the internal momentum exchanges cancel in pairs. The option 'It accelerates outward' is incorrect since acceleration would require a net external force, which is absent. The option 'It moves in a circle' has no physical basis without an external centripetal force. A consistency check confirms that the total linear momentum stays zero throughout, so the centre of mass remains exactly fixed, in full agreement with conservation of momentum for an isolated system.