The force of gravity pulling on a mass is given by the equation:

```

F = Gm1m2/r^2

```

Where:

* F is the force of gravity in newtons

* G is the gravitational constant, approximately 6.674 x 10^-11 N m^2 kg^-2

* m1 is the mass of the first object, in kilograms

* m2 is the mass of the second object, in kilograms

* r is the distance between the centers of the two objects, in meters