The final momentum of the skater is 3.77 m/s.
Momentum is the product of mass and acceleration. Recall that the principle of conservation of linear momentum states that total momentum before collision must equal the total momentum after collision.
Thus;
(50 Kg × 0 m/s) + (55Kg × 7.2m/s) = (50 Kg + 55Kg) v
v = (55Kg × 7.2m/s)/(50 Kg + 55Kg)
v = 396/105
v = 3.77 m/s
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