Posted by aichan on .
Two equal charges are separated by 3.7 x 10^10 m. The force between the charges has a magnitude of 2.37 x 10^3 N. What is the magnitude of q on the charges?
can some one explain to me how to do this step by step. Not that great at math hope you can help. Thanks

Physics 
drwls,
There is a formula for the force (F) between two charges (Q1 and Q2), separated by a distance R. It is called Coulomb's Law. It must be in your text or notes; otherwise they would not have assigned this problem.
The formula says
F = k Q1*Q2/R^2
where k is a constant that equals 8.99*10^9 N*m^2/C^2
In your case, Q1 = Q2 = q, so
F = k*q^2/R^2
Rearrange the equation algebraically and solve for q
q = R sqrt(F/k)= 3.7*10^10m*sqrt(2.636*10^13)M/m
= 1.9*10^16 Coulombs 
Physics 
aichan,
Thanks!

Physics (typo correction) 
drwls,
q = R sqrt(F/k)
= 3.7*10^10m*sqrt(2.636*10^13)C/m
C stands for Coulombs
I typed M where it should be C