Electric Potential Energy Among Multiple Charges kinda a

[seto6]

Electric Potential Energy Among Multiple Charges kinda aurgent

1. Homework Statement

Four point charges, fixed in place, form a square with side length d. (See image)

http://i23.photobucket.com/albums/b354/h4llw4x0r/notSoFast.jpg

The particle with charge q is now released and given a quick push; as a result, it acquires speed v. Eventually, this particle ends up at the center of the original square and is momentarily at rest. If the mass of this particle is m, what was its initial speed v?
Express your answer in terms of q, d, m, and appropriate constants. Use k instead of 1/4πe (where e = epsilon). The numeric coefficient should be a decimal with three significant figures.

2. Homework Equations

- Electric Potential Energy equation: U = k((Q1*Q2)/r)
- Relative Kinematics Equations

The Attempt at a Solution

Ui+Ki=Uf+Kf

Kf=0
you get following
Ki=-Ui+Uf

getting the potential for each charge
solving for v
v==[((2kq^2)/dm)((9/(.5^.4))-5-((5/(2^.5))]^.5 then simplifying
i got v=[((2kq^2)/dm)(4.192)]^.5
is this correct

 

[ehild]

Show your work, please.

ehild

 

[seto6]

i got it

 

[seto6]

v==[((2kq^2)/dm)((9/(.5^.4))-5-((5/(2^.5))]^.5 then simplifying
i should not get this v=[((2kq^2)/dm)(4.192)]^.5
i should get the following (6.24kq62/dm)^.5