You kick a soccer ball of mass 0.41 kg. the ball leaves your foot with an initial speed of 23 m/s. (a what is the magnitude of the impulse imparted to the ball by you?

Impulse = change in momentum

initial momentum = 0

final momentum = mv = 0.41 * 23 = 9.43 kg. m/s

Impulse = 9.43 - 0 = 9.43 kg. m/s

Impulse describes the change of momentum. Since we don't know the momentum of the soccer ball before the hit, this question is hard to answer. If you assume the momentum of the ball before the hit was p = 0, then the change in momentum is just Δp = Impulse = mv.