Newton's universal law of gravitation gives the force between two masses m₁ and m₂ separated by distance r as

1. Every particle attracts every other with a gravitational force. 2. F = G m₁ m₂ / r² where G = 6.67 × 10⁻¹¹ N m² kg⁻². 3. Force acts along the line joining the two particles, attractive only. 4. Inverse square in distance — same functional form as Coulomb's electric force. _Source: syllabus Physics, Ch 7 "Gravitation", §7.2_