Two particles of mass 1kg and 3kgmovetowardseachotherundertheirmutualforceofattraction.Nootherforceactsonthem.Whentherelativevelocityofapproachofthetwoparticlesis2\m/s,theircenterofmasshasavelocityof0.5m/s.Whentherelativevelocityofapproachbecomes3m/s,thevelocityofthecenterofmassis0.75m/s$.