Question Detail
Question
A 0.1 kg ball is dropped and hits the ground with a speed of 5 m/s. If it rebounds with a speed of 4 m/s, the magnitude of the impulse imparted to the ball by the ground is:
Correct Answer
Option D is the correct answer.
Detailed Explanation
Taking upward as positive, the initial velocity (before impact) is -5 m/s and the final velocity (after impact) is +4 m/s. The impulse I = Δp = m(vf - vi) = 0.1 kg * (4 - (-5)) m/s = 0.1 * 9 = 0.9 kg m/s.
Hint
Remember that velocity is a vector; consider the direction change.