Puzzler_fig-4.jpg
![](https://sigmapisigma.org/sites/default/files/Puzzler_fig-4.jpg)
Figure 4. Newton’s law of gravitation describes a dropped object falling. Here, G is the gravitational constant,3 M1 is the mass of the first object (the earth), M2 is the mass of the second object, and RE is the radius of the earth. The figure also shows the equation for gravitational potential energy U, where R is the distance between the two objects.