How Do You Calculate Electric Fields and Forces Between Multiple Point Charges?

[squissv]

I could really use some help with the following question:

Three point charges are located as follows: q1= (0,0) m, q2= (0,-0.120) m, q3= (0.272,0) m. Take q1= 4.37 x 10-9 C, q2= -3.00 x 10-9 C, q3= 6.41 x 10-9 C.

a) Find the vector electric field that the q2 and q3 charges together create at the origin. What are the x- and y-components of the electric field?

b) Find the vector force on the q1 charge. What are the x- and y-components of the force?

I have tried using the summation of Coulomb's Law and a dozen other approaches, that I can't really describe because they were so haphazard. Any help would be greatly appreciated. Thanks!

 

[dynamicsolo]

It will really be helpful to draw a diagram of this situation first. They have actually been very nice to you in having you figure out distances and components by placing q2 and q3 right on the x- or y-axis. (Most problems are not so tidy...)

Which way will the fields from q2 and q3 point at the origin? What are the distances of those charges from the origin? Do the charges produce two field components each?