A skater of mass 80.5 kg initially moves in a straight line at a speed of 4.90 m/s. The skater approaches a child of mass 41.0 kg, whom he lifts on his shoulders. Assuming there are no external horizontal forces, what is the skater's final velocity?

1 answer

Momentum is conserved:
80.5*4.90=(80.5+41)*V solve for V