**Velocity of Center Of Mass**

A closed, isolated system, the velocity of the center of mass of the system cannot be changed by a collision because, with the system isolated, there is no net external force to change it. To get an expression for v;,om, let us return to the two body system and one-dimensional collision.

Shows, in a series of freeze-frames, the motion of the center of mass for the completely inelastic collision is the target, and its initial linear momentum in . Body 1 is the projectile, and its initial linear momentum.Note that as the series of freeze-frames progresses to and then beyond the collision, the center of mass moves at a constant velocity to the right. After the collision, the common final speed V of the bodies is equal to because then the center of mass travels with the stuck-together bodies.

CHECKPOINT 3: Body I and body 2 are in a completely inelastic one dimensional collision. What is their final momentum if their initial momenta are. respectively, . (a) 10 kg m/s and 0; (b) 10 kg· m/s and 4 kg.

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