Physics for IGCSE & O level - Forces And Motion (Section 9 - No. 30)
What does it mean for a system to be 'closed' in terms of momentum?
No external forces act on the system.
Only external forces act on the system.
The system is isolated from its surroundings.
The total momentum is always zero.
הֶסבֵּר
A closed system experiences no net external force.