Calculating Net Force Between Two Dipoles

[kjintonic]

Homework Statement

Two identical dipoles, each of charge q and separation a, are a distance x apart, as shown in Fig. By considering forces between pairs of charges in the different dipoles, calculate the net force between the dipoles. Show that, in the limit a<<x, the force has magnitude
6kp^2/x^4, where p=qa is the dipole moment.

Homework Equations

E=2kp/x^3

The Attempt at a Solution

I have no idea where to start T^T

 

[Redbelly98]

They say to calculate forces between pairs of individual charges.

Which equation gives the force between two charges?

 

[kjintonic]

I really don't know... I am a 11th grader and I'm asked to do university stuff;;

oops i forgot the diagram

----- (- +) ---------------------------------(- +)----
--------a--------------------x-----------------a

EDIT: You mean kq1q2/r^2 ??

 

[kjintonic]

K now I understand that you have to use coulomb's law but how on Earth do i find q of one dipole?

 

[Redbelly98]

Yes, use Coulomb's law.

Just leave the charge as q and work through the algebra.