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Every mass attracts every other mass. Newton's law of universal gravitation says the force is proportional to the product of the masses and inversely proportional to the square of the distance between their centres.
Enter both masses and the distance. The default values are the Earth and a 70 kg person on its surface, which gives the person's weight, about 687 N, and g ≈ 9.82 m/s².
| Mass 1 (m₁) | 5,972,000,000,000,000,327,155,712 kg |
| Mass 2 (m₂) | 73,419,999,999,999,996,854,272 kg |
| Distance between centres (r) | 384,400,000 m |
| Gravitational force (N) | 1.98049e20 |
| Field strength of mass 1 at that distance (m/s²) | 0.00269748 |
The Earth and Moon pull on each other with about 1.98049e20 N.
Try this example →| Mass 1 (m₁) | 1 kg |
| Mass 2 (m₂) | 1 kg |
| Distance between centres (r) | 1 m |
| Gravitational force (N) | 6.6743e-11 |
| Field strength of mass 1 at that distance (m/s²) | 6.6743e-11 |
The force is just 6.6743e-11 N, which is why gravity between everyday objects is too small to notice.
Try this example →G = 6.674 × 10⁻¹¹ N·m²/kg² is tiny, so gravity only becomes noticeable when at least one mass is enormous, like a planet. It was first measured by Henry Cavendish in 1798 with a torsion balance.
Every two masses attract each other with a force F = Gm₁m₂/r², where r is the distance between their centres.
6.6743 × 10⁻¹¹ N·m²/kg². It is the same everywhere in the universe.
G is the universal gravitational constant. g is the acceleration due to gravity at a place, about 9.81 m/s² on Earth's surface.
It becomes one-quarter, because it depends on 1/r².