Final answer:
To determine if a system is internally stable, assess if it experiences a net force or torque opposite to the direction of displacement when perturbed. Stable equilibrium is indicated by a restorative force or torque, whereas unstable equilibrium occurs when the force or torque aligns with the displacement.
Step-by-step explanation:
Understanding Stability and Equilibrium
To determine whether a system is internally stable, we must assess its response to displacement. A system is in stable equilibrium if it experiences a net force or torque opposite to the direction of displacement when perturbed. If the system experiences a force or torque in the same direction as the displacement, it is in unstable equilibrium. A system in neutral equilibrium remains in equilibrium regardless of displacements.
When a system is not at equilibrium, it will shift in the direction that minimizes its potential energy or restores balance. This concept is grounded in the principle that a system with internal structure can have potential energy and that this energy is indicative of the interactions between objects within the system via conservative forces.
To conclusively determine the stability of a system, one must consider the forces or torques resultant from displacements in various directions. If the context were a supported wire, for example, vertical or horizontal displacements would need to be considered separately to evaluate the system's overall stability.