Coulombs law Physics

Question

FORMULA: K*Q1*Q2/R^2

keep in mind: the charge of a proton (and the negative charge of an electron) is equal to 1.60218 * 10^-19 C

1. What is the force between a proton and an electron which are 1 meter apart?

2. What is the force between two protons which are 0.01 meters apart?

3. What is the force between two electrons which are 1*10^-9, (or 0.000000001 meters) apart?

4. How far apart would a proton and an electron need to be to exert a force of 1 N on each other?

Answer 1

(I give the following answers to 3 sig figs because that's all I have found for k)

1) F₁ = (8.99 x 10⁹) (1.602 x 10^-19) (-1.602 x 10^-19) / (1 m)² = -2.31 x 10^-28 N.

2) F₂ = 2.31 x 10^-28 / (0.01)² = +2.31 x 10^-24 N.

3) F₃ = 2.31 x 10^-28 / (1 x 10^-9)² = +2.31 x 10^-10 N.

4) |1 N| = 2.31 x 10^-28 /r², r = 1.52 x 10^-14 m.