options

magnitude
attractive
force
air resistance
matter
weight
unbalanced
mass
??? forces act on an object that do not have a sum of zero, so they change the motion of the object.

The correct word to fill in the blank is "unbalanced". Unbalanced forces refer to the forces acting on an object that do not cancel each other out, resulting in a net force. This net force causes a change in the motion of the object.