momentum balance

Momentum balance is a principle in physics stating that the total motion (momentum) of a system changes based on the forces acting on it. If no external forces are present, the momentum remains constant; when forces act, they can increase or decrease an object's motion. Think of it as a way to track how the movement of objects shifts in response to pushes, pulls, or collisions. This principle helps predict how objects will move or respond in systems like fluids, vehicles, or even planetary motion, ensuring that all forces and resulting motions are balanced and accounted for.