Walker, Halliday & Resnick — Magnetic Fields: Problem 43

43 An electron has an initial velocity of $(12.0\hat{j} - 15.0\hat{k}) \text{ km/s}$ and a constant acceleration of $(2.00 \times 10^{12} \text{ m/s}^2)\hat{i}$ in a region in which uniform electric and magnetic fields are present. If $\vec{B} = (400 \mu\text{T})\hat{i}$, find the electric field $\vec{E}$.