Calc Work Req'd for 4 Charges in Figure

[shahin93]

Homework Statement

Consider the three charges in the figure below with Q1 = 2.8 µC, Q2 = 4.4 µC, and Q3 = -3.7 µC. A fourth charge q = -4.8 µC is brought from very far away and placed at the origin.

http://www.webassign.net/giocp1/18-p-009.gif

How much work is required in this process?
How much work is required to move q from the origin to a distance that is very far away?

Homework Equations

PE = -W = -F Δx = -qE Δx

The Attempt at a Solution

am i suppose to calculate the PE of each Q?

 

[ehild]

The work done on the charge q is equal to the change of its potential energy when it is moved from infinity to the origin.

ehild