How much work is done moving a 2.5 kg book to a shelf 3.0 m height?

The question is not well defined since the initial position of the box is not specified. Assuming that the box started from the floor, and also assuming that is finally brought to rest, then the answer is U=mgh=2.5kg(9.8m/s^2)(3.0m)=74j (is 73.5j but since we are multiplying two numbers with to sigmificant digits, the answer must have to sigmificant digits.) The same amount of kinetic energy will be generated when it reaches the floor.