How would we define positive and negative work in terms of energy? When the force and displacement are in opposite directions, we say the work done by the force is negative. When the force and displacement are in the same direction, we say the work done by the force is positive. However, how we would define the two in terms of energy. As far as I have understood this concept, I believe that whenever a force is supplying energy to a body(the work done gets converted into kinetic energy), it is positive work. But whenever, the force is draining the body of its kinetic energy and converting it into other forms (like thermal energy), it is negative work. Is this correct? If it isn't, what is the correct way to relate energy and work. And can someone please elaborate this topic? Thank you very much.