If F = k/r^2 what happens to r when y is doubled?

Question

So basically, it is for Physics (Coulombs Law) and I know you can use the full formula for it, but I want to know how to solve it using the fact that "the magnitude of the electrostatic force of interaction between 2 point charges is inversely proportional to the square of the distances between them."

Answer 1

I'm assuming you mean how do you double F by changing r.

So:

r = square root of (k/F)

clearly if you double F

r new = (r old)/(square root of 2)

r new =0.707x(r old)