A system of coplanar forces acting on a rigid body is equivalent to a non-zero couple. Which of the following statements about this system is not true?
The vector sum of the forces in the system is equal to the zero vector.
The sum of the moments of the forces about any point in the plane is constant.
The system can be brought into complete equilibrium by applying a single force of appropriate magnitude and line of action.
The system tends to cause rotation of the body without causing any translational acceleration of its centre of mass.
