What does it mean for a system to be in equilibrium? (physic w/ calc II)?

Question

I don't understand what it means for a system to be in equilibrium in this problem:

"Two objects, each carrying charge Q, are connected by a spring with force constant k, and relaxed length zero. When the system is in equilibrium, what is the distance between the two charges?"

I know I'm supposed to use this equation: F = (kQq)/(r^2)

Answer 1

Yes, you use the right one, F = (kQQ)/(L+x)^2

However do not confound k in that formula with k in F = -kx. You should use 2 different symbols for those 2 coefficients.

The distance between 2 charges will be L + x (I can't imgine of a spring with zero length)