1. The problem statement, all variables and given/known data This is the problem http://imgur.com/a/1XFlt 2. Relevant equations This is the given FBD http://imgur.com/a/CURqA 3. The attempt at a solution Now the car should have a tendency to slip down the ramp thus causing the frictional force to oppose this motion. But the frictional force is pointed down the ramp in this worked out problem. Can someone explain to me why this is?