In a closed system, the principle of conservation of momentum states that the total momentum before a collision is equal to the total momentum after the collision.
Before the collision:
- The momentum of the first ball (mass = 3 kg, momentum = 24 kg·m/s) is 24 kg·m/s.
- The second ball (mass = 1 kg) is initially at rest, so its momentum is 0 kg·m/s.
- The total initial momentum = 24 kg·m/s + 0 kg·m/s = 24 kg·m/s.
After the collision, the momentum of each ball will change due to the interaction. However, the total momentum of the system must remain constant at 24 kg·m/s.
So the correct statement is: The momentum of each ball changes, and the total momentum stays the same.