What is the basic concept of gravitation?

Gravitation is the universal mutual attraction between masses. Its magnitude follows:

F = G · (m₁ m₂) / r²

The force acts along the line joining their centres. On Earth it appears as weight:

W = m g, g \u2248 9.8 m·s⁻²

Key points

• Forces on the two bodies are equal and opposite.
• Inverse-square dependence on separation (r).
• Governs planetary orbits, tides, and satellite motion.
• Mass (kg) is intrinsic; weight (N) is gravitational force.