• # question_answer 36) Two particles A and B initially at rest, move towards each other under mutual force of attraction. At the instant when the speed of A is V and the speed of B is 2F, the speed of the center of mass of the system is A)  3V                              B)  VC)  1.5 V              D)  0

As there is no external force involved, so in conformance with the law, ${{F}_{ext}}=M{{a}_{cm}},$the acceleration of the center of mass is zero. Initially the center of mass is at rest, so it will continue to remain at rest. Hence, the correction option is [d].