1. The problem statement, all variables and given/known data 3 balls are on a ?string?/line?. Each are equally displaced, 72cm. Ball A has a charge of -50e5c, Ball B a charge of +25e2, Ball C -10e10. 1. What is the net force applied on the middle ball (Ball B)? 2. Assuming a force to the right(ungiven name of Ball D?) (of Ball C) is positive, find the net force applied on Ball C.. 2. Relevant equations F=kq1q2/d^2 k=9x10^9 n*m^2/c^2 3. The attempt at a solution These are all theoretical values.. I know the basic structure of the problem, but totally guesstimating the values. With that said.. To try and get net force of Ball B.. I did F(ab)=kq(a)q(b)/d^2 F(bc)=kq(b)q(c0/d^2 ... F(ab)+F(bc)=net force applied on Ball B.. I think that part was easy.. net force=-4.34x10^24, work on screenshot === Kind of lost for Part 2.. How do I find out the force for D? Or the charge of D? Or the distance (baby blue)? On the test, what I think I did was add charges A+B, set equal to C+D, or A+B-C=D.. Then use that value of charge for D, assume 72cm (I wanna know why I should assume), calculate force.. I don't think that's how it works though.. === I thought up an interesting theory just now.. All charges (balls) have same net forces, but vary +/-..? Here's another pic I forgot to draw it, but there's supposed to be a "blue vector equal to magenta vector".