What is the Force on Charge B Due to Charges A and C?

[euphoriax]

Homework Statement

Three charges A, B and C with charges respectively +3.2 x 10^-6 C and -7.8 x 10^-6 C are placed as seen in the diagram. What is the force on B because of A and C?

Homework Equations

F_E=kq₁q₂/r²

The Attempt at a Solution

d_AB = 2.5m
d_CB= 1.5m
k= 9.0x109 Nm2/c2

F_AB= kq₁q₂/r²
= (9.0x109)(3.2x10-6)(41.4x10-6)/(2.5)2
= 0.19 N

F_CB= kq₁q₂/r²
= (9.0x109)(-7.8x10^-6)(41.4x10^-6)
= -1.29 N

from here on, I'm not really sure what I am supposed to do...
any help would be aprreciated

thanks!

 

[daveb]

You didn't show the diagram, nor list the charge on B (I assume it's 41.6 uC) but you need to find the direction of the resultant vector.