1. The problem statement, all variables and given/known data Given: The friction between the block with mass 6 kg and the wedge with mass 18 kg is 0.27 . The surface between the wedge with mass 18 kg and the horizontal plane is smooth (without friction). The acceleration of gravity is 9.8 m/s^ 2. A block is released on the inclined plane (top side of the wedge). What is the minimum force F which must be exerted on the 18 kg block in order that the 6 kg block does not move down the plane? 2. Relevant equations Fnet = ma and possibly(?): Ff = uFn 3. The attempt at a solution Having the wedge in the problem is confusing me. The forces acting on the x axis of the 18 kg block are F applied and Fg parallel The forces acting on the x axis of the 6kg block are F frictional and Fg parallel. Fnet = ma / Fnet = 0 Fa + Fg(parallel) = 0 I think I am solving for Fa (18kg), i'm not sure. Fa = Fgsin20 Fa = (18kg)(9.8m/s2)sin20 Fa = 60.33 N I know the 6kg block plays a role, but i don't know how or where to incorporate it. I'm really confused, any help is appreciated.