What does Newton's First Law state?

• A. A body at rest tends to stay at rest, a body in motion tends to stay in motion, until acted upon by an outside force.
• B. Energy cannot be created nor destroyed.
• C. For every action there is an equal and opposite reaction.
• D. Objects move in the direction of the net force.

Answer: (A)

Inertia governs this idea: an object resists changes to how it is moving. An object at rest stays at rest, and an object in motion continues moving with the same speed and in the same direction unless a net external force acts on it. So without outside influences like friction, gravity, or a push, motion doesn’t change. That’s why this statement best captures Newton’s First Law.

Other options refer to different principles. Energy conservation is about how energy, not motion state, is preserved. The action-reaction idea describes forces that come in pairs (Newton’s Third Law). And the idea that objects move in the direction of the net force is a common misconception—the net force determines how the motion changes (the acceleration is in the direction of the net force), but the velocity itself isn’t simply “in the direction of” the net force at all times.