Change potential energy without doing work??? I'm sure this is a very elementary question, however, this is just one thing that has been confusing me in my General Physics w/ Calculus 1 class... They say, that if you are lifting a book at a constant velocity, no work is being done. This is because the acceleration going up, and gravity constant would have to be equal for the book to be moving at a constant velocity. This by itself i understand. however. later on in the course, we learned that Work=(delta kenetic energy)(force).. and -(delta potential energy)=(delta kenetic energy) also, by increasing the height of an object, you increase its potential energy. SO. as the book is rising, its gaining height...at this time its gaining potential energy.... if its gaining potential energy, that also means that its kinetic energy is decreasing, which would change the numbers in the work formula... how can one change potential energy without doing any work? again: a person raising a book vertically at a constant velocity is doing no work, yet changing the books potential energy. Potential energy is inversely related to kinetic enerby. Kinetic energy is a major variable in the work formula, thus it would have to change the value of work. If the value of work is changing here, how come the person is doing no work? maybe i havent made a whole lot of sense typing it out, but it's confusing the hell out of me.... if anyone can decipher what i've written here and come up with an explaination/clarification, i would very much appreciate it.