What is the force called that is equal in magnitude but opposite in direction to the resultant force?

The force that is equal in magnitude but opposite in direction to the resultant force is known as the equilibrant. In the context of physics and engineering, when multiple forces act on an object, the resultant force is the vector sum of these individual forces. To achieve a state of equilibrium, where the object does not accelerate, a force must be applied that has the same magnitude but acts in the opposite direction to this resultant force. This balancing force is termed the equilibrant.

Understanding this concept is crucial in power engineering as it relates to analyzing forces acting on systems, whether it's in machinery, structural components, or fluid dynamics. Ensuring that forces are balanced allows for safe and efficient operation of equipment and structures.

The other options do not accurately describe the force balancing the resultant. A component refers to the decomposition of a force into its constituent parts, an element might refer to a fundamental part of a system, and displacement is a measure of the change in position of an object, none of which convey the specific balancing role of the equilibrant.