A 10-Kg Object Moving 9

Multiple Choice

A 1.0-kg object moving 9.0 m/s collides with a 2.0-kg object moving 6.0 m/s in a direction that is perpendicular to the initial direction of motion of the 1.0-kg object. The two masses remain together after the collision, and this composite object then collides with and sticks to a 3.0-kg object. After these collisions, the final composite (6.0-kg) object remains at rest. What was the speed of the 3.0-kg object before the collisions?

A) 15 m/s
B) 10 m/s
C) 5.0 m/s
D) 20 m/s
E) 25 m/s