Find its speed v_final when it strikes the anode.?

Suppose a diode consists of a cylindrical cathode with a radius of 6.200×10−2 cm, mounted coaxially within a cylindrical anode with a radius of 0.5580 cm. The potential difference between the anode and cathode is 215 V. An electron leaves the surface of the cathode with zero initial speed (v initial = 0). Find its speed v_final when it strikes the anode.