Role of mass in this problem on electrostatics

[Dranzer]

Homework Statement

Positive charge Q is distributed uniformly over a circular ring of radius R.A particle with mass 'm' and a negative charge 'q' is placed on the axis at a distance 'x' from the centre.Find the force on the particle.Assuming x<<R, find the time period of oscillation of the particle if it is released from there.

Before I request for a solution, I would request someone to explain why the mass given here is relevant.

Secondly, can anyone please refer me a book/reference on electrostatics?I am fully comfortable with rigorous single variable calculus(I am in high school) and would not mind a book/reference that has really tough problems but explains the matter well.(My assessment is that I have not really understood the matter)

Edit:I can probably see that the x<<R condition is for approximation(or for some ignoring some quantity when it emerges in the answer or the steps leading to it)

 

[Ksitov]

Hi,

Why not?

To find the electrostatic force, i think (and I'm sure), the mass is'nt necessary.

But maybe for the time of oscillation no? I don't know.

So... You should to read Richard Feynman's books.

 

[vindarmagnus]

You are going to find a force which acts more or less like a spring (F = kx). Since you know that F = ma = md2x/dt2, you're going to wind up with a diff.eq. with m in it. The solution to it is a sine wave, in which you'll find your time constant.

spoiler: You are going to have to find the e-field by integrating the line charge, which in turn yields the force as F=qE. ps.Electromagnetic Fields by Wangsness is the best book on electromagnetism in my opinion, but it requires multi-variable.