A block of 3.1 kg is traveling in the -x direction at 5.1 m/s and a 0.9 kg block is traveling in the +x direction at 3.1 m/s.
(i) Determine the velocity vcm of the center of mass.
(ii) Subtract vcm from the velocity of each block to determine the velocity of each and every block in the center-of-mass reference frame.
(iii) After they make a head-on elastic collision, the velocity of each and every block is reversed (in the center-of-mass frame). Determine the velocity of each and every block in the center-of-mass frame after the collision.