# Potential energy of a system

1. Sep 21, 2006

### chuy

Hi,

We know that the gravitational potential energy of a mass m over the earth is:

$$-G\frac{mM_E}{r}$$

But the earth is very heavy, ¿if $$m\approx M$$ the gravitational potential energy of a system of two particles also is:

$$U(r)=-G\frac{mM}{r}$$ ???

Bye!

2. Sep 21, 2006

### Staff: Mentor

If m = ME = M, then the potential energy of a binary earth system would be $$U(r)=-G\frac{M^2}{r}$$.