1. The problem statement, all variables and given/known data A 15.6 kg block is dragged over a rough, horizontal surface by a 68.9 N force acting at 19.7 degrees above the horizontal. The block is displaced 4.59 m, and the coefficient of kinetic friction is 0.286. Find the work done by the 68.9 N force. How much energy is lost due to friction? 2. Relevant equations W=F (Δr) cos∅ Friction (kinetic)= μk* m*g 3. The attempt at a solution I found the work done by the 68.9 N force using the equation above to get 297.74 J. The energy lost due to friction should be simply the Force of kinetic friction multiplied by the displacement, right? I did 0.286*15.6 kg* 9.81 to get 43.77 N as the force of kinetic friction. Energy lost= Force friction * displacement i.e. 43.77 N * 4.59 m = 200.90 J, which is wrong. What am I missing?