Problem: "A smooth wedge of mass M has a triangular cross section with a side inclined at an angle theta to the horizontal base. The wedge can slide without friction along a horizontal support. Placed on the side of the wedge is a mass m that can slide with no friction along the side. Find vectors of the acceleration for the wedge and for m after the bodies are released from rest." I'm taking the x coordinate as the direction along the horizontal support and the y coordinate as the direction perpendicular to the horizontal support. Ok. I tried using the Lagrangian method and the problem then appeared to become extremely complicated. So I'm using Newton's laws to solve this. It just seems like the normal force which is exerted on the mass m by the block M will not be the same as that when the wedge at rest, since the mass m accelerates partially with the acceleration of the mass M but I'm not sure. Any ideas here?