What Is an Equilibrant Force?

Equilibrant forces are those that act on a body at rest and counteract the force pushing or pulling the body in the opposite direction. Equilibrant forces establish equilibrium for an object and make the object motionless. Equilibrant forces act on virtually every object in the world that is not moving.

The force of gravity is pulling down a cup sitting on a desk. The only way the cup can keep from crashing into the ground is if something pushes up on it at least as hard as gravity is pulling it down. The table or counter top holding up the cup supplies the equilibrant force, which keeps the cup up. If the table exerted more than equilibrant force on the cup, the cup would rise in the air.

Equilibrant forces can push or pull on an object as long as both forces are imparting the same type of force, but in the opposite direction. Sometimes, equilibrant forces work in concert with each other to offset opposing forces. For example, if three cables suspend a load, each is imparting a force that is equal to one-third of the force of gravity. Likewise, a load suspended by four cables imparts one-fourth of the pull of gravity on each cable.