A Frictionless Puck of Mass 1

Multiple Choice

A frictionless puck of mass 1.0 kg travels east at 90 m/s toward an initially motionless puck of mass 2.0 kg. When the pucks are 12 meters apart, the center of mass of the system is located

A) 3.0 m from the motionless puck.
B) 4.0 m from the motionless puck.
C) 6.0 m from the motionless puck.
D) 8.0 m from the motionless puck.
E) 12 m from the motionless puck.