Question

Calculate the gravitational force between a proton and electron separated by a distance of 1 femtometer. 

Given mass of proton = 1.67×10^–27 Kg 

Mass of electron = 9.1×10^–31 Kg 

and 1 femtometer = 10^–15 m

Answer 1

(Note that this force is extremely negligible. In comparision, the electrostatic force between the same proton and electron is:

This is very large compared to the gravitational force between them).