(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

I had a question in my physics class today that was relatively easy but what I was confused about was a misplaced negative sign. "An electron is rotating around a proton at a distance R. The mass of the electron is m_{e}and the charge is -e. Find the period."

2. Relevant equations

F_{c}=m_{e}v^{2}/R

F_{E}=kq_{1}q_{2}/R^{2}

T=2pi*r/v

3. The attempt at a solution

The solution was calculated equating the two equations given above. The problem arises when I plug in -e and +e for the charges. This leaves one side of the equation negative, which results in a negative period. How does the negative sign go away? Do I not include the sign for charges?

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# Homework Help: Negative sign in coulomb's law/centripetal motion question

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