**Gravitational Potential Energy**

We discussed the gravitational potential energy of a particle-Earth system. We were careful to keep the particle near Earth’s surface, so that we could regard the gravitational force as constant. We then chose some reference configuration of the system as having a gravitational.

Here, we broaden our view and consider the gravitational potential energy U of two particles. of masses m and M, separated by a distance r, We again choose a reference configuration with U equal to zero. However, to simplify the equations. the separation distance.

If our system contains more than two particles, we consider each pair of particles in turn, calculate the gravitational potential energy of that pair with as if the other particles were not there, and then algebraically sum the results. Applying to each of the three pairs.

The potential energy given by is a property of the system of two particles rather than of either particle alone. There is no way to divide this energy and say that so much belongs to one particle and so much to the other. However, if M ~ m, as is true for Earth (mass M) and a baseball (mass m), we often speak of “the potential energy of the baseball.

### Related Physics Topics for Tuition