Walker, Halliday & Resnick — Gauss' Law: Problem 33

33 An electron is shot directly toward the center of a large metal plate that has surface charge density \(-1.50 \times 10^{-6} \text{ C/m}^2\). If the initial kinetic energy of the electron is \(3.93 \times 10^{-17} \text{ J}\) and if the electron is to stop (due to electrostatic repulsion from the plate) just as it reaches the plate, how far from the plate must the launch point be?