Ratio of Electric Force to Gravitational force

[Winzer]

Homework Statement

It is known that the electric force of repulsion between two protons is much stronger than their gravitational attraction. For two protons a distance R apart, calculate the ratio of the magnitude of the repulsion to that of the attraction.

Homework Equations

F_{g}=\frac{Gm_{1}m_{2}}{r^2}
F_{e}=\frac{Kq_{1}q_{2}}{r^2}

The Attempt at a Solution

So the ratio \frac{F_{e}}{F_{g}} =\frac{Kq^2}{Gm^2}
I get 1.3E28 which is wrong. Why?

 

[Dick]

The equation is right. Hard to tell where you are going wrong with putting the numbers in.

 

[Winzer]

K=9.0E9
G=6.67E-11
Mass of proton aprox. 1.672E-27
Charge of a proton 1.602E-19
Right?

 

[Dick]

Fine. But looking at your number, I think you are forgetting to square the masses and charges.

 

[Winzer]

ok, i get 1.2E36 with 2 sig figs and still wrong.

 

[Dick]

I get 1.2355E36. So I disagree with who or whatever is telling you it's wrong.