1. The problem statement, all variables and given/known data 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 tire'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 tire's surface is 4.19E+03 V. What is the change in electrical potential energy during the shrinking process? 2. Relevant equations Change in electric potential energy = q (change in electric potential) 3. The attempt at a solution Delta U = qDelta V) = (4.89e-8C)(4190J/C-1350J/C) = 1.4e-4 J But that doesnt work.