A question about Electric Charge

[Daysi]

We know that the negative charge on the electron and the positive charge on the proton are equal. Suppose, however, that these magnitudes differ from each other by 0.00007%. With what force would two copper pennies, placed 1.2 m apart, repel each other? Assume that each coin contains 3 multiplied by 10^22 copper atoms. (Hint: A neutral copper atom contains 29 protons and 29 electrons.)

(From your answer, it should be obvious that the magnitude of the charge on a proton and the charge on an electron cannot possibly differ by as much as the given percentage.)

 

[rl.bhat]

Hi Daysi, welcome to PF.
Read the rules of PF. Before you ask for help you have to show you efforts.
What are the relevant equations you can use in the problem?

 

[Daysi]

ahh sorry. haven't read the rules yet.
I'm sure we can use Coulomb's law.
F=KQq/r²

 

[rl.bhat]

Your relevant equation is correct.What are the different forces acting on one pennies by the other?

 

[Daysi]

Repulsive force and attractive force? and the repulsive one is slightly larger?

 

[Daysi]

and q=29e?
I don't know how to do the rest...