the linear expansivity of the material of a cube of 12 * 10 12 * 10 raise to power - 6 k if the length of each of each side of a cube is 10 cm find the area of 11 face of the cube

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 260 v . an electron leaves the surface of the cathode with zero initial speed (v initial=0). find its speed vfinal when it strikes the anode.