Key Concepts: Newton’s Law of Gravitation

Newton's Law of Universal Gravitation

Every mass attracts every other mass with a force:

F = GMm/r²

• G = 6.674 × 10⁻¹¹ N·m²/kg² (gravitational constant).
• F is the force between masses M and m separated by distance r (center to center).
• The force is always attractive and follows an inverse-square law.

Key Points

• Double the distance → force decreases by a factor of 4.
• The force acts equally on both objects (Newton's third law).
• Near Earth's surface: F = mg, where g = GM/R² ≈ 9.8 m/s².