Given that,
Mass of particle 1, m₁ = 2.58 g = 0.00258 kg
Speed of particle 1, v₁ = 2.51 m/s
Mass of particle 2, m₂ = 6.53 g = 0.00653 kg
Speed of particle 2 = 0 (at rest)
To find,
The speed of centre of mass of the two particles.
Solution,
The formula for the centre of mass of the system is givn by :

So, the speed of the centre of mass is 0.71 m/s.