Alright so I have a question on the work done with constant acceleration up a hill. I was working an example problem that asked for the work a hiker must do on a 15.0 kg backback to carry it up a hill of height h = 10.0m with the hiker keeping a constant velocity (http://i1298.photobucket.com/albums/ag60/Physics_5/IMG_07961.jpg). I understood the solution when the problem had a constant velocity but not with a constant acceleration. I reasoned that if the hiker was accelerating up the hill, then a force acting parallel to the displacement was also present in addition to the force the hiker exerts upwards against gravity on the backpack. This would seem to indicate that the total force parallel to the displacement was greater than with constant velocity and that the work in the second situation was greater than the first. I didn't think that made sense because gravity is a conservative force but I don't understand why this explanation would not be valid.