1.Two particles lie on an x axis, particle 1 at x = 1 m and particle 2 at x = 2 m. If you gradually increase the mass of particle 1, what happens to the center of mass of the two-particle system? 2.If an external force acts on a system of several objects, can the external force change the net momentum of the system? 2. Relevant equations ((m2)/(m1+m2))d 3. The attempt at a solution I'm not sure for the first question if it moves in the negative or positive direction of x or if it does not move at all..