1. The problem statement, all variables and given/known data a) Determine the work a hiker must do on a 15.0-kg backpack to carry it up a hill of height h=10.0 m b) determine the work done by gravity on the backpack, and c)the net work done on the backpack. Assume the motion is at constant velocity. I don't understand why the question asks you the work done by hiker and done by gravity. What's the difference? Is that the work done by hiker is in the direction of the motion, i mean the slope. However, the work done by gravity is in the direction of the altitude of the hill, height? On the book, the diagram is like a backpack, and then the force which points upward is the force by Hiker, the force points downward is the gravity. Hope you can clarify, thanks.