The final momentum of the ball is 3.8 kgm/s.
The impulse received by the ball is equal to change in momentum of the ball.
J = ΔP
where;
ΔP = P₂ - P₁
P₂ = ΔP + P₁
The final momentum of the ball is calculated as follows;
P₂ = 8 + (- 0.1 x 42)
P₂ = 8 - 4.2
P₂ = 3.8 kgm/s
Learn more about change in momentum here: https://brainly.com/question/7538238