Question

which law states that the total momentum of a closed system remains constant if no external forces act on it? law of conservation of energy; newtons first law; law of conservation of momentum; law of universal gravitation

Explanation:

The question describes the principle that total momentum in a closed system with no external forces stays unchanged. The Law of Conservation of Momentum directly matches this definition. The Law of Conservation of Energy relates to energy, Newton's First Law covers inertia, and the Law of Universal Gravitation describes gravitational attraction between masses.

Answer:

Law of Conservation of Momentum