Question

A 1.0 kg ball has a velocity of 12 m/s downward just before it strikes the ground and bounces up with a velocity of 12 m/s upward. What is the change in momentum of the ball?

A) 0 kg x m/s
B) 12 kg x m/s, downward
C) 12 kg x m/s upward
D) 24 kg x m/s downward
E) 24 kg x m/s upward

Answer 1

The change in momentum of the ball is 24 kg·m/s upward since it reverses direction from downward to upward at the same speed.

Step-by-step explanation:

The change in momentum of a 1.0 kg ball that goes from 12 m/s downward to 12 m/s upward is calculated by finding the difference in the final and initial momentum. Since momentum is defined as mass times velocity (p = mv), the initial momentum (downward) is 1.0 kg × (-12 m/s) = -12 kg·m/s and the final momentum (upward) is 1.0 kg × 12 m/s = 12 kg·m/s. The change in momentum (Δp) is the final momentum minus the initial momentum: Δp = 12 kg·m/s - (-12 kg·m/s) = 24 kg·m/s. Therefore the change in momentum is directed upward, which corresponds to answer choice E: 24 kg·m/s upward.