Relatively simple vectors question, but no numbers....

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Homework Help Overview

The discussion revolves around a problem in electrostatics, specifically focusing on the vector forces acting on a point charge due to two other identical point charges. The original poster presents a scenario where the forces between the charges are analyzed, particularly the net force on one of the charges.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to break down the forces into components and applies the principle of superposition. They express uncertainty about their calculations and the use of a specific triangle ratio for simplification. Other participants question the assumptions regarding the polarity of the charges and seek clarification on the mathematical approach.

Discussion Status

The discussion is ongoing, with participants providing feedback on the original poster's reasoning and calculations. Some guidance has been offered regarding the use of trigonometric ratios, but multiple interpretations and approaches are still being explored.

Contextual Notes

There are constraints mentioned, such as the prohibition of using the cosine law and the requirement to work with specific triangle ratios. The discussion also highlights the assumption that all charges are identical, which is critical to the problem setup.

Bagwan
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The unit right now is electrostatics, but this question is really just vectors, nothing to do with charges or anything... anyways here is the info:

1. Homework Statement
Three identical point charges, A, B, and C are located as shown here:

M9bYJ9L.png


The force A-on-C is the same as the force B-on-C. What is the net force on C?

Homework Equations



I think the only equation I need is the superposition of force principle:
FnetC = FAonC + FBonC

The Attempt at a Solution


[/B]
Breaking into components (not allowed to use cosine law for some reason):

I know X-axis force is 0 as the 2 forces cancel out (since they are both equal and in opposite directions).

FnetCY = FAonC * cos(45) + FBonC * cos(45)

Not sure what else I can do though...

EDIT: I messed around with the 1-1-sqrt(2) triangle and I'm not sure if this is right, but is (2/sqrt(2)) * FAonC the right answer?

EDIT 2: Yes, that's the right answer, but sqrt(2) * FAonC is also right.

Because guess what, 2 divided by squareroot(2) is THE SAME THING AS squareroot(2)...
 
Last edited:
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seems okay to me
 
assuming the charges on the charges on the corners A and B are all the same polarity
 
rpthomps said:
assuming the charges on the charges on the corners A and B are all the same polarity

Yeah they are all identical.

rpthomps said:
seems okay to me

How would I use the 1-1-squareroot2 triangle to simplify it more? I'm not sure how to do that part too well.
 
replace your cos45 statement with the equivalent ratio
 

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