Three identical masses are kept at the corners of an equilateral triangle ABC. A moves towards B with a velocity V, B moves towards C with velocity V, and C moves towards A with same velocity V. Then the velocity of centre of mass of the system of particles is

Given data: An equilateral triangle ABC is placed in space, cornered with three identical masses with names of respective vertices. Velocity of all particles are identical which is equal to V and moving towards its adjacent particle in clockwise manner.

The acceleration of centre of mass of the system remains zero if the total external forces acting on a system is zero. 

Thus, here, the Velocity of the center of mass is zero.