1. The problem statement, all variables and given/known data Consider the mass m1 on a simple incline plane. It passes from point A downwards with the velocity v0 and stops at point B (still on the plane). What is the work done by the normal force on mass m during the complete motion? 2. Relevant equations 3. The attempt at a solution In my book it says zero but I dont think it is because the mass moves diagonally down which shows movement in x and y axis. Since the normal force acting on the mass isnt perpendicular to the y axis movement. It should do work in the opposite direction. What do you think?