In the context of Newton's law of universal gravitation, what force is primarily responsible for the mutual attraction that drives mass movements (such as planets orbiting stars or objects falling toward Earth)?

• A. The strong nuclear force acting over astronomical distances
• B. The electromagnetic force between neutral objects
• C. The buoyant force due to atmospheric pressure differences
• D. The gravitational force between masses

Answer: (D)

Verified step by step guidance

1. Identify the fundamental forces in nature: gravitational, electromagnetic, strong nuclear, and weak nuclear forces.
2. Understand that the strong nuclear force acts only at subatomic distances, holding protons and neutrons together inside the nucleus, and does not operate over astronomical distances.
3. Recognize that electromagnetic forces act between charged particles, but neutral objects do not experience significant electromagnetic attraction or repulsion at large scales.
4. Note that buoyant force is a result of pressure differences in a fluid and is not a fundamental force; it cannot explain planetary motions or free fall in vacuum.
5. Conclude that Newton's law of universal gravitation describes the gravitational force as the mutual attraction between masses, which governs planetary orbits and objects falling toward Earth.