- 113

- 1

**1. Homework Statement**

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. Homework 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?