the vector position of a 3.50g particle moving in the xy plane varies in time according to r1=3it+2jt^2 where t os on seconds and r is in centimeters. At the same time, the vector position of a 5.00g particle varies as r2=3i-2it^2-6jt^2. At t=2.50s, determine (a) the vector positio of the center of mass of the system. (b) the linear momentum of the system, (c) the velocity of the center of mass, (d) the acceleration of the center of mass, and (e) the net force exerted on the two-particle system.