Two identical spheres of mass m are released from rest at the negative plate of a parallel-plate capacitor and accelerate toward the positive plate through the same potential difference ΔV. Sphere A carries charge +q, and sphere B carries charge +2q. Ignore gravity and edge effects. Which statement describes the speeds of the spheres just before they reach the positive plate?
a) Sphere B is faster; vB=2vA
b) Both spheres reach the plate with the same speed, vB=vA
c) Sphere B is faster by a factor of 2; vB=2vA
d) Sphere A is faster than sphere B, vA>vB