When the electrons pass the anode they leave the electric field. Then there is no more acceleration.
So the equations for a uniform linear motion are usable:\[\begin{array}{rll}x(t) & = & v_{\rm{end}}\cdot t \\ v(t) & = & v_{\rm{end}}\\ a(t) & = & 0\end{array}\]
The electrons move with the velocity they get while passing the acceleration zone.
Classic
Relativistic
Exercises
