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## Homework Statement

Two conducting spheres of the same size have charges q1=-4x10^-6

and q2 = 8x10^-6C,and their centers are seperated by 3.0cm

a) what is the force between them?

b) what would be the force if the spheres were touched together and again seperated by the same distance

## Homework Equations

well we could use F=kq1q2/r^2

## The Attempt at a Solution

for a) I plugged in 9x10^9 x -4x10^-6 x 8x10^-6 all divided by .09 which gives -3.2 but the answer is -320N.can someone explain my why?

for b) i dont know how it would start.

i tried doing several things. use the -320 as the seperated force and

get the force of the one together and add them together.

something like that but i don't know how it gives 40N.