A skater of mass 74.5 kg initially moves in a straight line at a speed of 5.10 m/s. The skater approaches a child of mass 37.5 kg, whom he lifts on his shoulders. Assuming there are no external horizontal forces, what is the skater's final velocity?

Answer 1

Linear momentum along the straight line is conserved, assuming neglible skate friction during the lift,

74.5*5.10 m/s = (74.5 + 37.5)* Vfinal

Solve for Vfinal.

Vfinal = 5.10 m/s(74.5/112)= 3.39 m/s