Calculate the force of gravity on the 0.60- kg mass if it were 1.3×107 m above earth's surface (that is, if it were three earth radii from earth's center).

The gravitational force between two objects is given by:

where
G is the gravitational constant
m1 and m2 are the masses of the two objects
r is their separation

In this problem, the first object has a mass of , while the second "object" is the Earth, with mass . The distance of the object from the Earth's center is ; if we substitute these numbers into the equation, we find the force of gravity exerted by the Earth on the mass of 0.60 kg: