Gravity Drives Planetary Motion

Steps:

• Identify the phenomenon: Earth's stable orbit around the Sun requires a centripetal force to maintain circular motion.
• Recall fundamental forces: Among the four fundamental forces, gravity acts over large distances between massive bodies like planets and stars.
• Apply to the solar system: Newton's law explains that the Sun's gravitational pull keeps Earth in orbit, balancing its tangential velocity.
• Match to options: Gravitational force directly corresponds to choice C.

Why C is correct:

• Newton's law of universal gravitation states F = G(m1 m2)/r², where the Sun's mass attracts Earth, providing the force for orbital motion.

Why the others are wrong:

• A: Elastic forces act within deformed materials like springs, not between celestial bodies.
• B: Electrostatic forces involve charged particles and are negligible over astronomical distances without significant charge separation.
• D: Magnetic forces arise from moving charges or magnets and do not dominate planetary-scale attractions.

Final answer: C