What is the electric potentional for these charges?

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Homework Help Overview

The discussion revolves around calculating the electric potential energy for a system of three charges located at specified coordinates. The charges include two positive charges and one negative charge, and participants are exploring how to compute the potential energy using the appropriate equations.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the need to calculate the distances between charges using the Pythagorean theorem and question how to correctly apply these distances in the potential energy equations. There is also confusion regarding the contributions of each charge to the overall potential.

Discussion Status

Some participants have attempted calculations but report discrepancies in their results. There is ongoing clarification about the correct distances and the method of summing the contributions from each charge. Multiple interpretations of the problem are being explored, particularly regarding the wording and the setup of the potential energy calculations.

Contextual Notes

Participants note that the problem is sourced from Webassign, and there is a request for the original question to ensure clarity. There is also mention of potential confusion stemming from the wording of the problem.

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Homework Statement



Find the electric potential energy for the following array of charges: charge q1 = +4.0 µC is located at (x, y) = (0.0, 0.0) m; charge q2 = +3.0 µC is located at (4.0, 3.0) m; and charge q3 = −1.0 µC is located at (0.0, 3.0) m.

_____ mJ

Homework Equations



U=kq1q2/r12
U=kq1q3/r13
U=kq2q3/r23

The Attempt at a Solution



Obviously, I just plug in the charges and the k constant, 8.99 x10^9, but I don't know what to put in for r. Do I have to calculate x and y components and add them up?
 
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well i hope you know that each charge constrabute to potential. so say there are 1,2,3 charges. if you want to calculate the potential due to charge 1,2 on 3 just do 1 on 3 and 2 on 3. then add them up.

BA
 
see "relevant equations". I already know I have to add them all up. I just don't know how to calculate r.
 
oh my mistake.

so we know x2 + y2=r2 <---Pythagorean theorem

from this and the corrdinate you are given you can find r
 
I tried that, but it says it's wrong.

Using it, r12 would be: sqrt. (4^2 + 3^2) = 5

r13: sqrt. (0^2 + 3^2) = 3

r23: sqrt. (3^2 + 0^2) = 0

and plugging it into the equation kq1q2/r12, kq1q3/r13, kq2q3/r23 and adding them all up gives me 5.9 x 10^-4 Joules, which is 0.59 millijoules, which it says is wrong.

Can you please help me? I don't know what I'm doing wrong.
 
Ammora said:
I tried that, but it says it's wrong.

Using it, r12 would be: sqrt. (4^2 + 3^2) = 5

r13: sqrt. (0^2 + 3^2) = 3

r23: sqrt. (3^2 + 0^2) = 0<---- this is wrong, it should be 3

and plugging it into the equation kq1q2/r12, kq1q3/r13, kq2q3/r23 and adding them all up gives me 5.9 x 10^-4 Joules, which is 0.59 millijoules, which it says is wrong.

Can you please help me? I don't know what I'm doing wrong.

btw can you post the original question. and is this from mastering physics?
...so are we trying to find the electric potential of q1 due to q2 and q3?.. because I am kinda confussed by the wording
 
Find the electric potential energy for the following array of charges: charge q1 = +4.0 µC is located at (x, y) = (0.0, 0.0) m; charge q2 = +3.0 µC is located at (4.0, 3.0) m; and charge q3 = −1.0 µC is located at (0.0, 3.0) m.

We have to find the electric potential for all 3 charges.
 
No, it's from Webassign, not a book.
 
first take the + and - into account
next say distance btw q1 and q2 take the differnece btw the point then use that to find distance...

oh mastering physics is like Webassign..

i used Webassign for math
 

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