Why Is My Calculation of Coulomb's Force Incorrect?

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Discussion Overview

The discussion revolves around a calculation of Coulomb's force between two charged metal spheres, specifically addressing the impact of temporarily bringing the spheres into contact before measuring the force at a distance. The scope includes theoretical understanding and application of Coulomb's law.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant presents a calculation using Coulomb's law but receives an incorrect result according to an online service.
  • Another participant questions whether the effect of the spheres being in contact was considered in the calculation.
  • A subsequent reply suggests that since the spheres are conductive, their charges would redistribute when in contact, implying a change in the effective charges before calculating the force.

Areas of Agreement / Disagreement

Participants have not reached a consensus on how to correctly account for the effect of contact on the charges of the spheres, indicating multiple competing views on the correct approach to the problem.

Contextual Notes

The discussion highlights the importance of considering charge redistribution in conductive materials when calculating electrostatic forces, but does not resolve the specific steps needed to adjust the initial calculation.

LTZach
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I thought this would be a basic physics problem, but I'm not getting the right answer, here's the problem:

There are two identical small metal spheres with charges 27.5 μC and −19.119 μC. The distance between them is 8 cm. The spheres are placed in contact then set at their original
distance. Calculate the magnitude of the force between the two spheres at the final position. The Coulomb constant is 8.98755 × 109 N · m^2/C2 .
Answer in units of N.

I used the formula, F=K*((q1*q2)/r^2)). I converted the charges using the 10^-6 conversion.

So, F=(8.98755*10^9)*(27.5*10^-6 * 19.119*10^-6) all over 0.08^2 and I got 738.3448 N.

The answer is incorrect according to the online service my class uses, what did I do wrong?
 
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Did you take into account that they were temporarily placed in contact?
 
How would I do that?
 
The spheres are metal and therefore conductive. What happens to the charges when two charged conductive materials come in contact?
 

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