Question

which is always true in a closed system? (1 point)

acceleration is not constant.

momentum is conserved.

mass is not conserved.

velocity is constant.

Explanation:

• For "Acceleration is not constant": In a closed system, acceleration can be constant (e.g., uniform circular motion has constant centripetal acceleration magnitude, or a system with constant net force has constant acceleration by \( F = ma \)), so this is false.
• For "Momentum is conserved": By the law of conservation of momentum, in a closed system (no external net force), the total momentum of the system remains constant. This is a fundamental principle.
• For "Mass is not conserved": In a closed system (for non - relativistic cases, which is the context here usually), mass is conserved. Mass can't be created or destroyed within a closed system, so this is false.
• For "Velocity is constant": Objects in a closed system can interact (e.g., collide), changing their velocities. So velocity isn't necessarily constant.

Answer:

B. Momentum is conserved.