When an object is in the balance. The external force is a force on the object, there must be internal resistance.Total size is equal to the external force of the object taken.
When the subject is in equilibrium External force acting on the object must have strong internal resistance equal to the total size of the object is subjected to external forces.
When the object is in a state of equilibrium. External forces that act on objects must have a strong internal resistance.Total size = external force of the object were treated.