Question

A(n) 0.5 kg soccer ball approaches a player horizontally with a speed of 10.6 m/s. The player illegally strikes the ball with her hand and causes it to move in the opposite direction with a speed of 19.9 m/s. What is the magnitude of the impulse delivered to the ball by the player? Answer in units of kg · m/s.

Answer 1

Answer: - 25.2 kgm/s

Explanation: The mass of the ball is 0.5kg, and the initial velocity = 10.6m/s.

The final velocity is in opposite direction of the initial hence final velocity (v) = - 19.9 m/s

Impulse = change in momentum = final momentum - initial momentum.

Final momentum = mass × final velocity

Final momentum = - 19.9 × 0.5

Final momentum = - 9.95 kgm/s

Initial momentum = mass × initial velocity

Initial momentum = 0.5 × 10.6 = 5.3kgm/s

Change in momentum = final momentum - initial momentum = - 19.9 - 5.3

Change in momentum = - 25.2 kgm/s

The negative sign implies that the change in momentum is the opposite direction relative to the first.