1. The problem statement, all variables and given/known data Imagine a right angled triangle ABC. AC is the hypotenuse. The actual problem is: An inlined plane is kept along AC (5m metre long). An object A is kept at the base of it. A force is applied on it parallel to AC. AB is 3m long. Account for the difference between the rise in potential energy (the object reaches A) and the actual work down by the force. 2. Relevant equations Nil 3. The attempt at a solution I think that there is also a horizontal displacement which accounts for the difference. My book says its entirely pure friction. But i dont agree. please help.