Calculating electrostatic force on particles

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Homework Help Overview

The discussion revolves around calculating the electrostatic force between charged particles using Coulomb's law. Participants are analyzing the components of the force in different directions based on the charges involved.

Discussion Character

  • Mathematical reasoning, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are attempting to calculate the x and y components of the electrostatic force, questioning the correctness of their calculations and the assumptions made regarding the signs of the forces. There is a focus on the relevance of charge signs and the need for careful unit conversions.

Discussion Status

Some participants are providing numerical calculations and comparing results, while others are questioning the assumptions made about the forces' directions and magnitudes. There is an ongoing exploration of the correct approach to determine the x-component of the force, with no explicit consensus reached yet.

Contextual Notes

Participants are discussing the implications of charge signs and the need for accurate unit conversions, particularly from centimeters to meters. There is an emphasis on understanding the vector nature of the forces involved.

Jrlinton
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Homework Statement



Phy 204.PNG

Homework Equations


F=(kq1q2)/d^2

The Attempt at a Solution


So it should be fairly easy to use "parts" to come up with each answer
Part a
Because particle 1 has no pull in the x direction I should be able to ignore it when finding the x component of the force
Fx=k*q3*q4/a^2+k*q3*q2/(a*sqrt2)^2*cos45
=7.46E-4 N
This was incorrect and I did not attempt part 2 as I figured my mistake would carry over to that similar calculation
 
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Check your calculation. I get something else. Spell it out if you want it checked.
 
8.99E9*(9.5E-8)*(-9.5E-8)/(2.03E-3)+8.99E9*(9.5E-8)(-5E.7)/(4.05E-3)cos45deg
=-0.114623N
it seems that I made a mistake on my cm to m conversion and if I remember correctly this should be absolute value of the charges so
=0.114623N
 
Numerical value same as what I found.

Jrlinton said:
if I remember correctly this should be absolute value of the charges
No. You are asked for an x-component, which can be negative or positive. Make a sketch to find the right sign. What does the F in your relevant equation represent ?
 
I realized this after I sent it. Both q2 and q4 are opposite charges of q3 so they are both attractive forces. In regards to the y component q1 will repel q3 while q2 will again be attractive and by glance you can tell the effect of q1 will be greater than q2 you can assume that the answer will be negative in the y direction
 
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Assuming is one thing, calculating is better :smile:.
 

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