Newton's first law of motion is essentially a statement about
- A. the acceleration produced by a force
- B. inertia, the tendency of a body to resist a change in its state of motion
- C. action and reaction pairs
- D. the conservation of energy
Explanation
A body continues at rest or in uniform motion in a straight line unless a resultant force acts, so the law defines what a force actually does: it changes motion rather than maintaining it. Mass is the measure of that inertia. This is why a passenger lurches forward when a bus brakes suddenly.