Question

multiple choice question
in situations and problems involving momentum, a closed system is defined as one that does not gain or lose

energy

mass

momentum

temperature

Explanation:

In the context of momentum, a closed system for momentum conservation is one where there is no net gain or loss of mass (since momentum depends on mass and velocity, and a closed system in momentum terms relates to mass conservation for the system's particles; energy, momentum itself, or temperature are not the defining factor for a closed system in momentum problems here—mass conservation is key as the system doesn't exchange mass with the surroundings, which is crucial for momentum conservation principles).

Answer:

B. mass