A tiny hole is made in the center of the negatively and positively charged plates of a capacitor, allowing a beam of electrons to pass through and emerge from the far side. If $40.0 \mathrm{V}$ are applied across the capacitor plates and the electrons enter through the hole in the negatively charged plate with a speed of $2.50 \times 10^{6} \mathrm{m} / \mathrm{s},$ what is the speed of the electrons as they emerge from the hole in the positive plate?