1. The problem statement, all variables and given/known data Is work done by something always negative and work done on something always positive, or do you determine that by the cos theta portion of the work equation. Also, can potential energy be negative 2. Relevant equations W=Fdcos theta PE=mgd 3. The attempt at a solution I've been generalizing, and sometimes it makes me come out with the wrong sign, so that's why I need clarification.