Work to move charge to infinity?

[awertag]

Homework Statement

The figure below shows three charges at the corners of a rectangle of length x = 0.55 m and height y = 0.35 m.

http://www.webassign.net/walker/20-23alt.gif

(a) How much work must be done to move the +2.7-µC charge to infinity?

Homework Equations

W=($$\Delta$$V)(q)
V3=potential at the spot of the charge
Q3=2.7e-6 C

The Attempt at a Solution

W=/\VQ
W=V3(Q3)
then try to solve for V3=KQ3/r3 but i know i can't because i don't have an r because there's no reference point for it. So, is there another way to solve for potential or am i just going about the whole thing wrong?

thanks very much

--aweg

 

[tiny-tim]

hi awertag!

(have a delta: ∆ and try using the X² and X₂ icons just above the Reply box )

the work done against two (or more) forces is the sum of the work done against each force …

∫(∑F).d = ∑(∫F.d) ​

 

[awertag]

haha thanks for the delta :)
i actually got the problem, i just was having trouble finding the potentials but I've got it now. Thank you for taking the time to respond, and have a great day!