Understanding Coulomb's Law: Calculating Force on a Line of Charges

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Homework Help Overview

The discussion revolves around Coulomb's Law and the calculation of the force on a charge due to other charges positioned along a line. The original poster presents a specific scenario involving three charges and expresses confusion regarding the distances used in the calculations.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to understand the distances between charges and how they relate to the forces calculated using Coulomb's Law. Some participants question the interpretation of the distances and suggest that the positions of the charges are being confused with the distances between them.

Discussion Status

The discussion is progressing with participants clarifying the positions of the charges and addressing the original poster's confusion. A participant has provided insight into the coordinate system being used, which appears to help the original poster understand the situation better.

Contextual Notes

The original poster references a physics book and expresses a struggle with the material, indicating a potential lack of familiarity with the concepts involved in Coulomb's Law and charge interactions.

mr_coffee
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Hello everyone, I've been having the hardest time getting the hang of coulobs law. I got a physics book, physics for complete morons. The question is simple enough:

Consider a line of charges, q1 = 8.0 micro C at the orginin, q2 = -12 micro C at 2.0 cm, and q3 = 10 micro C at 4.0cm. What is the force on q3 due to the ohter two charges?

So you find F31 and u find the F32 and then add up the two forces to find your answer. But to find F31 they used a distance of .04m which confuses me. If the charges are as follows:

(q1)---(q2)-------(q3)
.02m .04m

Why wouldn't the distance from q1 to q3 be .06m? :bugeye:

Thanks.
 
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Yeah it is 0.06m, maybe you are misunderstanding what they are trying to do. What did they use for F32?
 
I suspect that those are the positions of the charges (their coordinates along the axis), not the distances between them. Calling it the x-axis, the charges are at:
x1 = 0m
x2 = 0.02m
x3 = 0.04m

Make sense?

And welcome to PF, by the way!
 
ahhh, how simple. Thanks Doc you were right!
 

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