1. Mass of the objects: The more massive the objects, the stronger the gravitational force between them. This is a direct relationship - double the mass, double the force.
2. Distance between the objects: The force of gravity weakens rapidly as the distance between the objects increases. This is an inverse square relationship - double the distance, reduce the force to one-fourth.
3. Gravitational constant (G): This is a fundamental constant of nature that determines the strength of gravity. It's a very small number, which is why gravitational forces are weak unless one or both objects are very massive.
In summary, the formula for gravitational force is:
```
F = G * (m1 * m2) / r^2
```
Where:
* F is the force of gravity
* G is the gravitational constant (approximately 6.674 x 10^-11 N m^2/kg^2)
* m1 is the mass of the first object
* m2 is the mass of the second object
* r is the distance between the centers of the objects
Let me know if you'd like to explore any of these properties in more detail!
