Halliday, Resnick & Walker — Electric Fields: Problem 44

44 At some instant the velocity components of an electron moving between two charged parallel plates are $v_x = 2.5 \times 10^5 \text{ m/s}$ and $v_y = 5.0 \times 10^3 \text{ m/s}$. Suppose the electric field between the plates is uniform and given by $\vec{E} = (120 \text{ N/C})\hat{j}$. In unit-vector notation, what are (a) the electron’s acceleration in that field and (b) the electron’s velocity when its $x$ coordinate has changed by $2.0 \text{ cm}$?