Distance of Electrons with Electrostatic Force

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SUMMARY

The discussion centers on calculating the distance between two electrons on Earth's surface for their electrostatic force to equal the weight of one electron. The relevant equation used is Coulomb's Law, expressed as Fe = (1 / 4∏ε0) X (q1q2 / r^2). The initial calculation yielded a distance of 15.98 m, while the correct answer is approximately 5.08 m, derived by considering the weight of the electron as me x 9.81 m/s². Participants identified a potential oversight involving the π constant in the calculations.

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kgal
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Homework Statement


How far apart must two electrons be placed on the Earth's surface for there to be an electrostatic force between them equal to the weight of one of the electrons?


Homework Equations



Fe = (1 / 4∏ε0) X (q1q2 / r^2)


The Attempt at a Solution



I set Fe = me- (electrical force = mass of electron).

and solved for r = sqrt( q^2 / (me-)(4∏ε0) ) = 15.98 m, but the answer should be 5.08 m..
 
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hi kgal! :smile:
kgal said:
I set Fe = me- (electrical force = mass of electron).

and solved for r = sqrt( q^2 / (me-)(4∏ε0) ) = 15.98 m, but the answer should be 5.08 m..

hmm … 15.98/5.08 = π …

did you lose a π somewhere?​
 
The WEIGHT of an electron = me x 9.81, I got the answer to be 5.02m
 
i attached the picture.

I don't see the flaw...
 

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thanks technician!

i thought that i have to ignore g because its so small compared to the electrical forces...
 

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