1. The problem statement, all variables and given/known data A charge of 3.0 μC is distributed uniformly throughout the volume of plastic sphere with a radius of 10.0 cm. An identical plastic sphere with charge 3.0 μC is shot directly at the center of the first sphere, from very far away. The mass of each sphere is 5.0 X 10^-5 kg. If the first sphere is held fixed, how fast must the second sphere be launched so that the two spheres touch one another? How will this change if the first sphere is free to recoil? 2. Relevant equations F = (q1*q2)/(r^2*4*pi*ε) E = Q/(4*pi*ε*r^2) 3. The attempt at a solution I honestly don't know where to start on this one. I get the feeling it has something to do with the field causing an acceleration, which would mean I need to use kinematics, but the force would be increasing as the charged spheres got closer, and I don't know how to handle changing acceleration.