Talk:FHSST Physics/Electrostatics/Electrostatic Force

I can only see this in Worked Example 60 Coulomb's Law II

Step 3 :

Calculate the electrostatic force using Coulomb's Law:

Failed to parse (unknown function\rmC): \begin{matrix}F_E&=&k\frac{Q_1 Q_2}{r^2}=k\frac{e\cdot e}{1\AA^2}\\&=&(8.99\times10^{9}\rm N\cdot m^2/C^2)\frac{(-1.60\times10^{-19}{\rm C})(-1.60\times10^{-19}\rmC)}{(10^{-10}\rm m)^2}\\&=&2.30\times10^{-8}\rm N\end{matrix}

Hence the magnitude of the electrostatic force between the electrons is 2.30\times10^{-8}\rm N. (Note that the electrons carry like charge and from this we know the force must be repulsive. Another way to see this is that the force is positive and thus repulsive.)

Step 4 :

Calculate the gravitational force: Failed to parse (unknown function\cdotm): \begin{matrix}F_E&=&G\frac{m_1m_2}{r^2}=G\frac{m_e\cdot m_e}{(1\AA)^2}\\&=&(6.67\times10^{-11}{\rm N\cdotm^2/kg^2})\frac{(9.11\times10^{-31}{\rm C})(9.11\times10^{-31}{\rm kg})}{(10^{-10}{\rm m})^2}\\&=&5.54\times10^{-51}{\rm N}\end{matrix}

The magnitude of the gravitational force between the electrons is 5.54\times10^{-51}\rm N