## University Physics with Modern Physics (14th Edition)

The magnitude of their gravitational force of attraction is $\frac{G~M^2}{4R^2}$.
We can use Newton's law of gravitation to find the magnitude of their gravitational force of attraction. Note that the distance between their centers is 2R. $F = \frac{G~M~M}{(2R)^2}$ $F = \frac{G~M^2}{4R^2}$ The magnitude of their gravitational force of attraction is $\frac{G~M^2}{4R^2}$.