1. The problem statement, all variables and given/known data A block slides down an inclined plane with friction. It is sliding at a constant speed. The only forces acting on the block are its weight and contact forces due to the incline. The inclined plane is stationary. The inclined plane is a wedge that is highest on the left (eg. you would slide down towards the right). That is the way the block is sliding. Which way does the force exerted by the block on the inclined plane point? 2. Relevant equations 3. The attempt at a solution Well, I think there's a friction force pointing along the inclined plane towards the upper left and a normal force 90 degrees to the inclined plane pointing down. Adding these gives one force, pointing towards the left (straight to the left). But apparently the answer is straight down (like along the y axis). I don't understand why, can anyone help?