The force of gravity pulling downward and the force of the table pushing upwards on the book are of equal magnitude and opposite directions. These two forces balance each other. Yet there is no force present to balance the force of friction. ... Unbalanced forces cause accelerations.
Balanced forces do not cause a change in motion. When balanced forces act on an object at rest, the object will not move. ... Forces that cause a change in the motion of an object are unbalanced forces. Unbalanced forces are not equal and opposite.
