An object is said to be in equilibrium if it obeys the following rules:
Be more accurate, if the resultants of all forces and couples acting on it are both zero, the body will be in static equilibrium.
Alternatively, if the forces are concurrent and their vector sum is zero, then the body will be in equilibrium.
Try the equilibrium java applet. See if you can make it balanced.
The force will form a couple which will make the object rotate in anti-clockwise direction.