What is gravity?

• A. Attractive force between all things with mass
• B. Repulsive force between objects with mass
• C. Force that shapes the orbit of planets
• D. An effect caused by motion of light

Answer: (A)

Gravity is the attractive force that pulls objects with mass toward one another. This fundamental interaction explains why things fall to the ground, why the Earth pulls on the Moon, and why planets stay in orbits around the Sun. In the classical view, every pair of masses exerts a pull on each other, and the strength weakens with distance. That endless pull between all masses is what governs motion on both everyday and cosmic scales, so describing gravity as an attractive interaction captures its essence.

Saying gravity is a repulsive force isn’t consistent with how it acts in the real world. Describing gravity as the force that shapes planetary orbits is true in terms of one of its consequences, but the defining idea is the mutual attraction between masses. And gravity isn’t caused by the motion of light; light is influenced by gravity, but gravity itself arises from mass and energy, not from how light moves.