In both voltage and gravity, I know that the work done in moving a particle between two points is independent of the path taken. For my problem, it states "what if the path did make a difference?" I'm suppose to design a device/machine that will move a particle or object repeatedly between two points, a to b and then back, where the energy necessary to go from a to b is half the energy that is returned when the mass moves from b to a long a different path. Also show that this device can do an unlimited quantity of useful work. The question doesn't really state any parameters on the design. We are learning about Kirchhoff's voltage law and how it was derived. I can't think of anything logical. Can anyone offer some advice? Any help will be appreciated. Thank you.