Resumen de Negative Work Done by a Person
If I slowly raise a heavy book one meter up in the air, I do positive work. This work corresponds to an energy transfer. I lose chemical food energy that is consumed by my muscles to lift the book upward. Energy is gained by the book-Earth system in the form of gravitational potential energy that is stored in the gravitational field. 1 But what happens if I slowly lower the book back down by one meter to its original location? The book-Earth system loses all the energy it gained and returns to its starting configuration. I have done negative work this time. But my muscles do not regain their original chemical energy! Where did the lost energy go?
