# Does potential energy have measurable corresponding mass?

1. Aug 18, 2014

### graciousgroove

When a rubber band is stretched, or a battery is charged, or two massive objects are separated, the potential energy of all these systems increases in each situation. Now say that any of these systems were suspended in space. If we were to measure the gravitational field of the uncharged battery, and then charge the battery (for the sake of simplicity, lets say we can charge the battery without changing its center of mass) would the charged battery have a stronger gravitational field because the total energy of the system has been increased??

If this were true, wouldn't it be hypothetically possible to create an arbitrarily massive system, simply by arranging the components of that system in a way that is very complicated and contains a lot of potential energy?

2. Aug 18, 2014

### Drakkith

Staff Emeritus
Yes, potential energy increases the mass of an object. For example, a charged battery is slightly more massive than a dead battery. During discharge, that potential energy is turned into another form and leaves the battery, so there must be less total energy in a discharged battery than a charged one, resulting in a decrease in mass.

I don't believe you can create an "arbitrarily" massive system, as you can only fit so much potential energy into any one system. To increase it further you would need to keep adding more parts.