Q22. In a system two particles of masses $m _ { 1 } = 3 \mathrm {~kg}$ and $m _ { 2 } = 2 \mathrm {~kg}$ are placed at certain distance from each other. The particle of mass $m _ { 1 }$ is moved towards the center of mass of the system through a distance 2 cm . In order to keep the center of mass of the system at the original position, the particle of mass $m _ { 2 }$ should move towards the center of mass by the distance $\_\_\_\_$ cm.