A hockey puck is traveling to the left with a velocity of v=10 when it is struck by the hockey stick

We have to calculate the impulse of a hockey puck.

Imp = m * (v 1 - v 2) = m * Δ v

v 1 = - 10 i m/s,

v 2 = (20 * cos 40°) i + (20 * sin 40°) j =

= (20 * 0.766) i + (20 * 0.64278) j = (15.32 i + 12.855 j) m/s

Δ v = (15.32 i + 12.855 j) - ( - 10 i) =

= 15.32 i + 12.855 j + 10 i = 25.32 i + 12.855 j

| Δv | = √ (25.32² + 12.855²) = √806.35 = 28.4 m/s

Imp = 0.2 kg * 28.4 m/s = 5.68 N-s

Answer: D) 5.68 N-s.