Physics
posted by Filip on .
a charged particle is in point (2, 3, 8) and has a charge Q1 = 5x1010C. Another particle is at (5,7,0) and has a charge Q2 = 3x1010C. Calculate how much work needed to move the first particle to the point (0, 7.2) using the electric field

The initial distance between the particles is
Sqrt(9 + 16 +64) = sqrt89 = R1
The final distance between the particles is
Sqrt(25 +196 +4) = sqrt225 = 15 = R2
Calculate the change in potential energy
K Q1 Q2 (1/R1  1/R2)
K is the Coulomb constant
You need to state the units for position. Is it meters? 
I need to calculate this using the integral formula which is: W =  ∫ F dl =  q ∫ E dl
Where E = 1 / 4piε0 * R(vector) / R^3
I am just confused in what Efield I have to use and do I need to calculate X,Y & Z separately?? 
And regarding the position of the charges it only says its positions in the room for example charge 1 is : (x,y,z) = (2,3,8). But it should be in Meters if SIunit is needed..

The method I described is a shortcut that will give the correct answer. If you are going to use F*dl integrals, you have to specify the path the moviong charge follows, not just the end points. Ultimately, the answer only depends upon how much the distance between the charges changes, and the productof the two charges.