Newton's First Law of Inertia

Steps:

• Recall Newton's first law: An object remains at rest or in uniform motion unless acted on by a net external force.
• Examine each choice for direct alignment with this principle.
• Identify the option that restates the law verbatim without additions.
• Eliminate options introducing unrelated concepts like motion types or force-momentum relations.

Why A is correct:

• It directly restates Newton's first law, defining inertia as constant velocity without net force.

Why the others are wrong:

• B: Satellite's velocity changes direction in circular motion, requiring centripetal force, violating constant velocity.
• C: Water drop experiences gravity after leaving umbrella, causing acceleration, not constant velocity.
• D: Describes Newton's second law (F = Δp/Δt), not the first.

Final answer: A