A single electron orbits a lithium nucleus that contains three protons (+3e)?

Question

the radius of the orbit is 1.76 x 10^-11m. Determine the kinetic energy of the electron.

Answer 1

mv^2 / r = k*3e^2 / r^2

=> Kinetic energy

=(1/2) mv^2

= k * 3e^2 / 2r

= (9x10^9) * 3 * (1.6 x 10^-19)^2 / 1.76 x 10^-11 J

= (27 x 2.56) x 10^-18 / 1.76 J

= 3.93 x 10^-17 J

(calculations have not been rechecked)