# Homework Help: Two Electric Balls Hanging

1. Sep 15, 2009

### TheLegace

1. The problem statement, all variables and given/known data
Assume each ball is loosing charge at a rate of 1.20nC/s, as what instantaneous relative speed do the balls approach each other initially.
m=11.2g L=122cm x=4.70cm

http://img40.imageshack.us/img40/9708/electballs.jpg [Broken]

2. Relevant equations

I figured since the value given is a rate it would be the dq=-1.20nC/s, but I am not entirely sure what exactly this rate is referring to, I am assuming it would be derivative to charge q. But the units are C/s. I am a bit lost now, because I don't know where to start, if I use Coloumbs law with dF and find force and divide it by mass that is given then I can maybe find acceleration and continue from there, but somehow I doubt it.

I know that v=dx/dt, maybe I have to find a way to find these equations from the rate given.

Thank You

Last edited by a moderator: May 4, 2017
2. Sep 15, 2009

### TheLegace

Ok, I have missed one huge glaring detail, that x is defined as x=[q^2L/2(pi)mg)]^1/3, I guess taking the derivative of this will result in the answer I am still trying to work it out, but it is not a simple derivative.