I'm thinking about how to teach work and energy to my introductory
class. I like the interpretation of work as a mechanical transfer of
energy, as I think it clears up the sign issues. However, I've seen
energy defined as "the ability to do work", which of course dumps us
into a circular definition. Outside of that, however, I'm not sure
how to define energy in general.
How do other people handle this chicken and egg problem?