On an ice skating rink, a girl of mass 50 kg stands stationary, face to face with a boy of mass 80 kg. The children push off of one another, and the boy moves away with a velocity of +3 m/s.
What is the final velocity of the girl?
–1.9 m/s
+1.9 m/s
–4.8 m/s
+4.8 m/s
