Final answer:
Adequate stability against overturning moment refers to a moment that prevents a structure from overturning, which is crucial in maintaining equilibrium and preventing accelerated rotation.
Step-by-step explanation:
The adequate stability against overturning moment refers to a situation where the moments that would cause a structure to tip over are outweighed by those keeping it stable. Specifically, the answer to the student's question is 2) A moment that prevents a structure from overturning.
This is part of the conditions for equilibrium, particularly the second condition which involves avoiding accelerated rotation and maintaining a constant angular velocity. A stable equilibrium occurs when a system displaced from this equilibrium experiences a net force or torque that pushes it back towards its original position.
For instance, if a wrecking ball hits an unsupported concrete wall near the top, the wall is more likely to fall by rotating at its base rather than falling straight down because the torque created at the pivot (base of the wall) causes it to tip over. However, if the same force strikes at the base, the likelihood of the wall falling over depends on how well it is anchored at the base.