# Why can't i calculate this system of electric potential?

1. Sep 25, 2005

### mr_coffee

Hello everyone, i'm having troubles figuring out why this problem is wrong. In the quark model of fundamental particles, a proton is composed of three quarks: two "up" quarks, each having charge +2e/3, and one "down" quark, having charge -e/3. Suppose that the three quarks are equidistant from one another. Take the distance to be 1.32 10-15 m.

(a) Calculate the electric potential energy of the system of only the two "up" quarks.
wrong check mark eV
(b) Repeat for all three quarks.
eV

for (a) I used the following i found in the boook:
The electric potential enegery of a system of fixed point charges is equal to the work that must be done by an external agent to assemble the sytem, bringing each chage in from an infintie distance.

U = W = q2V = (1/4Pi*Eo)((q1*q2)/r);
U = (1/4Pi*Eo)(2/3)^2/(1.32e-15m) = 3.03E24 eV which is wrong, what did i mess up? Thanks.