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.
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.