doh! that doesn't solve the problem i am working on.
here is wha ti am working on:
An electron moves in a circular orbit about a stationare proton. The centripetal force is provided by the electrostatic force of attraction between the proton and the electron. The elctron has a kinetic energy of 2.18e-18 J
(a)what is the speed of the electron?
(b)what is the radius of the orbit of the electron?
i used k=.5mv^2 to find that velocity from the electron is 2.19e6 m/s. for part b i am not sure how to find the r. do i use the centripetal force formula:
F = mv^2 / r
if i use this then i need to know F. F is the electrostatic force? what is the electrostatic force?