
Originally Posted by
Harold14370
No, that is not right. If you lift the book up to a higher elevation, you have given it potential energy, which requires you to do net work on it.
When you apply 49 newtons without moving the object, you are not doing work. (Work=force*distance.) But if you apply 49 newtons and the object is moving, then you are doing work of 49 newtons multiplied by the distance you have moved it. If it is moving at a constant velocity, then the work done is proportional to the time that it is moving at that velocity. During that time it is gaining height, hence potential energy.