When a mass and case travel at constant velocity, the mass remains in its ____________ position.

The correct answer is that the mass remains in its center position when it travels at constant velocity. This concept is rooted in Newton's first law of motion, which states that an object in motion will remain in motion with the same speed and in the same direction unless acted upon by an external force. When both the mass and the case are moving at a constant velocity, the center of mass of the system does not change relative to the system itself.

In dynamic scenarios, the center position of an object refers to the average position of all its mass, which remains unchanged when no external forces are acting on it. So, while the mass moves along with the case, its relative position concerning the center of the mass remains constant, reinforcing that it is effectively maintaining its position within the system regardless of the movement.