Question

fill in the blank: it is the definition of _______ that explains a books tendency to continue to move, once it is moving; and it is an unbalanced force, such as friction, acting on the book that stops its forward motion.

Explanation:

Inertia is the property of an object to resist changes in its state of motion. A book's tendency to continue moving once it is in motion is due to inertia. Gravity is a force that attracts objects towards each other. Momentum is the product of an object's mass and velocity. Acceleration is the rate of change of velocity. Since the question is about an object's tendency to keep moving (a property related to its state of motion resistance), inertia is the correct term.

Answer:

inertia