Can someone please give me a nudge in the right direction on how to solve this problem? The electric field intensity at a distance r from the center of a uniformly charged sphere of radius R and total charge Q is Qr/4πεR^3, when r < R. Such a sphere corresponds to the Thomson model of the atom. Show that an electron in this sphere executes simple harmonic motion about its center and derive a formula for the frequency of motion. Evaluate the frequency of the electron oscillations for the case of the hydrogen atom and compare it with the frequencies of the spectral lines of hydrogen. How do i even start?