To bring a body into equilibrium, an additional force must be applied equal in magnitude but opposite in direction to the:

The correct answer is that an additional force must be applied equal in magnitude but opposite in direction to the equilibrant. The equilibrant is defined as the force that, when applied to a system, brings it into a state of equilibrium. In physics, for a body to be in equilibrium, the net force acting on it must be zero. This means that if there are multiple forces acting on the body, the equilibrant force must exactly counterbalance the vector sum of those forces, also known as the resultant.

The resultant is essentially the combined effect of all the forces acting on the body. When identifying the equilibrant, it is calculated as the negative of the resultant; hence, it directly provides the required force needed to achieve equilibrium.

Choosing the equilibrant highlights its specific role in balancing forces, while the resultant simply represents the total force without directly implying the need to counteract. Understanding these concepts is crucial in power engineering, where equilibrium conditions often define safe and stable operational parameters for systems.