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Homework Statement
Hi everyone and thank you in advance for your time. I just had this problem on a physics exam (that everyone in the class bombed, and I mean everyone, including the best students). I honestly couldn't care less about the grade, but I really want to understand where I went wrong on this one... a picture outlining the problem parameters is attached.
The problem is asking how much work is required to move a particle charge q, mass m traveling at constant velocity v in a circle, from r_{1} to r_{2}.
Homework Equations
Kinetic Energy = [itex]\frac{1}{2}[/itex]mv^{2}
Electric Potential Energy = [itex]\frac{kQq}{r}[/itex]
The Attempt at a Solution
The particle has initial kinetic and potential energy, hence the total energy of the system when the particle is on the r_{1} line is:
[itex]\frac{1}{2}[/itex]mv_{0}^{2} + [itex]\frac{kQq}{r1}[/itex]
and the final energy of the system at r_{2} will be:
[itex]\frac{1}{2}[/itex]mv_{f}^{2} + [itex]\frac{kQq}{r2}[/itex]
So would the work done by an outside force simply be equal to the difference in the total energies of the system? This seems to make sense but I have a feeling that its simpler than this... I am also almost certain that voltage comes into play here, but I'm not quite sure where.
Thanks again.
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