Every mass pulls every other mass
Newton's law of gravitation says any two masses attract each other with a force that grows with their masses and shrinks fast with distance.
G is the gravitational constant, a tiny 6.674 × 10⁻¹¹, which is why you feel gravity only next to something planet-sized.
The inverse-square law
Because distance is squared, doubling the separation cuts the force to a quarter, and tripling it to a ninth. Move twice as far from a planet and its pull on you drops fourfold.
Why the Earth wins
Two people standing close do attract each other, but with a force far too small to feel — a few micronewtons. The Earth's enormous mass is what turns the very same law into the weight you stand on.
Frequently asked questions
What is the gravitational force formula?
Newton's law of gravitation: F = G·m₁·m₂ / r², where m₁ and m₂ are the two masses, r the distance between their centres, and G the gravitational constant. The force is in newtons.
What is the gravitational constant G?
G is 6.674 × 10⁻¹¹ N·m²/kg². It is extremely small, which is why gravity between everyday objects is far too weak to notice and only becomes strong near planet-sized masses.
What is the inverse-square law?
Because distance is squared in the formula, the force falls off fast with separation. Double the distance and the force drops to a quarter; triple it and it drops to a ninth.
Why don't I feel gravity between everyday objects?
Because G is tiny and everyday masses are small, the pull between two people standing close is only a few micronewtons — millions of times weaker than the Earth's pull on them.
What is the difference between mass and weight?
Mass is how much matter something has and does not change. Weight is the gravitational force on that mass, F = m·g, so the same object weighs less on the Moon even though its mass is unchanged.