What is the change in electrical potential energy during the shrinking process? for your own interest, what was the work needed to change the potential energy? what does the work needed to bring this change?

A tire of radius 32.5 cm has a surface that is conducting. A charge of 4.89*10-8 C is then placed on the surface. The potential on the balloon's surface is 1.35E+03 V. Later, suppose that some of the air is let out of the tire, so that the radius shrinks to 10.5 cm, the new potential on the balloon's surface is 4.19E+03 V.