Which statement reflects Newton's first law of motion?

Which statement reflects Newton's first law of motion?

• A. F = ma
• B. An object at rest stays at rest and an object in motion stays in motion
• C. For every action, there is an equal and opposite reaction
• D. Energy cannot be created or destroyed

Answer: (B)

Inertia and the idea of resisting changes in motion are what this question is testing. Newton's first law states that an object at rest stays at rest and an object in motion stays in motion unless a net external force acts on it. The statement that captures this exactly is that principle: nothing changes velocity unless something external pushes or pulls.

Think about it in everyday terms: a ball on a smooth surface will stay at rest until someone nudges it, and a ball rolling on a frictionless surface keeps moving in the same direction at the same speed unless friction or another force slows it down or stops it. That tendency to keep doing what it’s already doing is inertia.

The other statements describe different ideas. F = ma is Newton's second law, linking force to acceleration. The third law says every action has an equal and opposite reaction, which is about interaction pairs. The statement about energy not being created or destroyed is the conservation of energy, a separate principle.