A charge Q is at the origin. A second charge, Qx = 2Q, is brought to the point x = a and y = 0. A third charge Qy is brought to the point x = 0, y = a. If it takes twice as much work to bring in Qy as it did Qx, what is Qy in terms of Q?
My main problem in this (Besides an incompetent professor ) is connecting the relationships of Qy, Qx, and Q, specifically Qy and Q. Also, I believe my formula for work to bring in a charge
(W = (k * Qx * Qy)/ R)
Might be wrong.
The Attempt at a Solution
W = work to bring in charge.
Wy = 2*Wx
Wx = (k * Q * Qx)/a => Wx = (k * 3Q)/a
Wy = (k * Q * Qy)/a
(k * Q * Qy)/a = 2 * (k * 3Q)/a => (k * Q * Qy)/a = (k * 6Q)/a
And here's where I start to have problems; constant 'k' and 'a' get canceled out, fine and dandy. However, the 'Q' also gets canceled out, which is bad as that's what I want my final answer in terms of.
Also, am I over thinking this, or do the vectors of Qy and Qx not allow me to make this connection?
Thanks to anyone can help, and I hope to have a pleasant stay here at Physics Help