Which of the following is NOT an example of an unbalanced force?

The statement regarding the book resting on a table accurately highlights a situation where forces acting on an object are balanced. In this case, the force of gravity pulling the book downward is equal to the upward support force exerted by the table. Because these forces counterbalance each other, the book remains at rest, demonstrating a state of equilibrium rather than acceleration or change in motion.

On the other hand, the other examples provided involve unbalanced forces that result in motion or changes in velocity. For instance, a car accelerating forward indicates that the driving force from the engine exceeds the resistive forces such as friction and air resistance, leading to an increase in speed. Similarly, a soccer ball being kicked experiences a net force that causes it to accelerate in the direction of the kick, while a person pushing a door to open it applies a force greater than the opposing forces (like friction in the hinges), resulting in the door's motion.