A ball with original momentum +4.0 kg x m/s hits a wall and bounces straight back without losing any kinetic energy. The change in momentum of the ball is:
Correct answer: D. -8Ns
- A. +4 kg·m/s
- B. -4 kg·m/s
- C. +8 kg·m/s
- D. -8Ns
Explanation
The following is the solution: When a ball bounces off a wall and changes direction without losing any kinetic energy, it experiences a change in momentum due to the reversal of its velocity. The change in momentum (Δp) of an object is given by the final momentum (pf) minus the initial momentum (pi): Δp = pf - pi where: pf = final momentum of the ball pi = initial momentum of the ball Given that the ball has an original momentum of +4.0 kg·m/s, and it bounces back without losing any kinetic energy, its final momentum (pf) will be -4.0 kg·m/s (opposite direction). Now, we can calculate the change in momentum: Δp = (-4.0 kg·m/s) - (+4.0 kg·m/s)Δp = -8.0 kg·m/s So, the change in momentum of the ball will be -8.0 kg·m/s. The negative sign indicates the momentum has reversed the direction during the collision with the wall.
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