Which law explains inertia, the resistance to changes in motion?

Which law explains inertia, the resistance to changes in motion?

• A. Newton's First Law of Motion
• B. Newton's Second Law of Motion
• C. Newton's Third Law of Motion
• D. The Law of Gravity

Answer: (A)

Inertia is the resistance to changes in motion, and Newton's First Law explains exactly that. It says an object at rest stays at rest and an object in motion stays in motion unless a net external force acts. This captures inertia because motion only changes when a force intervenes. For example, a hockey puck would keep skating at the same speed and direction on a nearly frictionless surface, and a parked car stays put until someone applies a push or pull. The other laws describe how forces cause acceleration or how forces come in pairs, not the tendency of motion to resist change. The Law of Gravity describes attraction between masses, not inertia.

Inertia is the resistance to changes in motion, and Newton's First Law explains exactly that. It says an object at rest stays at rest and an object in motion stays in motion unless a net external force acts. This captures inertia because motion only changes when a force intervenes. For example, a hockey puck would keep skating at the same speed and direction on a nearly frictionless surface, and a parked car stays put until someone applies a push or pull. The other laws describe how forces cause acceleration or how forces come in pairs, not the tendency of motion to resist change. The Law of Gravity describes attraction between masses, not inertia.