What is the definition of inertia?

What is the definition of inertia?

• A. The resistance to change in the state of rest or motion.
• B. The tendency for objects to move in circles.
• C. The force causing acceleration.
• D. The energy of motion.

Answer: (A)

Inertia is the property of matter that resists changes in its motion or rest. That means an object at rest tends to stay at rest, and an object moving at a constant velocity tends to keep moving that way unless a net external force acts on it. Mass is a measure of inertia—the greater the mass, the greater the resistance to changing motion. The statement that best captures inertia is that it resists changes in the state of rest or motion. For example, a heavy cart resists starting to move, and once it’s rolling, it tends to keep going straight unless a force (like friction or a push) alters its path. The other ideas describe related concepts but not inertia itself: a tendency to move in circles describes circular motion and the forces that produce it, not the resistance to change; the force causing acceleration is the net external force that can change motion; and the energy of motion refers to kinetic energy, which is a measure of motion, not the resistance to changing that motion.

Inertia is the property of matter that resists changes in its motion or rest. That means an object at rest tends to stay at rest, and an object moving at a constant velocity tends to keep moving that way unless a net external force acts on it. Mass is a measure of inertia—the greater the mass, the greater the resistance to changing motion.

The statement that best captures inertia is that it resists changes in the state of rest or motion. For example, a heavy cart resists starting to move, and once it’s rolling, it tends to keep going straight unless a force (like friction or a push) alters its path. The other ideas describe related concepts but not inertia itself: a tendency to move in circles describes circular motion and the forces that produce it, not the resistance to change; the force causing acceleration is the net external force that can change motion; and the energy of motion refers to kinetic energy, which is a measure of motion, not the resistance to changing that motion.