Electric charge, simple problem for most of you.

1. The problem statement, all variables and given/known data

A) Two electric charges each with the charge of -35 nC is 0.70m apart from each other. With how big of a force do they impact each other?

B) A small metallic ball has a positive charge of 25nC. A particle with the charge +2.0nC is affected by a repellent force that's caused of the metallic ball. At what distance is the force of the ball 60 µN.


2. Relevant equations



3. The attempt at a solution

I'd really love some clues or perhaps links to equations that are relevant to these types of problems. I've a hard time imagining that these problems are hard once you know the relevant equations since this is the most basic physics there is.

 

Thank you very much!

 

Is this correct? F = q1*q2 / r^2 = -35*-35/0.49 = 2500?

And if so, what is the power measured in?