Which of Newton's Laws is applied in problems involving static equilibrium?

In problems involving static equilibrium, Newton's First Law is particularly relevant because it states that an object at rest will remain at rest unless acted upon by a net external force. This principle is key in understanding static equilibrium, where the sum of all forces and the sum of all torques acting on an object equals zero. Essentially, when an object is in static equilibrium, it is not accelerating, which reflects the condition outlined in the First Law.

In the context of static equilibrium, if all forces acting on the object balance perfectly, it will remain in its state of rest. Thus, if there are no unbalanced forces acting on an object, it will not move, confirming the application of Newton's First Law in this scenario.

The other laws mentioned deal with different aspects of motion: Newton's Second Law relates to the acceleration of an object when a net force is applied, while Newton's Third Law concerns action-reaction pairs of forces. The Universal Law of Gravitation is specifically about the attraction between masses and does not apply directly to the concept of static equilibrium.