Electric Charge and Spring Force Problem

[laurenflakes]

Homework Statement

A small sphere with a charge of 2.36 microCulombs is attached to a relaxed horizontal spring whose force constant is 88.6 N/m. The spring extends along the x axis, and the sphere rests on a frictionless surface with its center at the origin. A point charge Q = - 8.55 microCulombs is now moved slowly from infinity to a point x = d > 0 on the x axis. This causes the small sphere to move to the position x = 0.124 m

Homework Equations

I don't even know where to begin with this problem :(

The Attempt at a Solution

I don't really understand the concept or even how to begin to solve this problem.. any explanation of the concept or where to start would be greatly greatly appreciated!

 

[collinsmark]

Finding the force on that spring would be a reasonable start (what force would cause a displacement of 0.124 m?). Coulomb's law will help you with the rest.