When the rope does not move
In a tug of war two teams pull a rope in opposite directions. When one team pulls harder than the other the rope moves their way. But at the moment both teams pull with equal force, the rope moves neither way and stays still.
Figure to be added
The rope is still not because no force acts on it. Both forces are acting all the while — they are equal and opposite, so what they add up to is zero.
Being still is not the absence of force
An object that does not move is not an object with no force on it. It is an object whose forces add up to nothing.
The word equilibrium
In this situation the rope is said to be in equilibrium under the two forces applied to it. This whole chapter is about that word: when a body is in equilibrium, and what conditions the forces acting on it must satisfy for it to be.
Over the next two pages we look at two simple cases of two forces — an object hanging from a spring balance, and a sphere hanging from a thread.