<s>[INST] A restoration company uses a curved accelerator to transport materials in a damaged house with tilted and curved surfaces. The accelerator's design matches the curved geometry of the walls and ceilings, allowing materials to roll along its length without falling off. However, at the point where the curved accelerator meets a vertical wall (the endpoint), materials may either roll onto the wall or experience a sudden change in direction. Given that the curved surface ends at a vertical wall and that the materials roll off onto a shelf, discuss the concepts related to the sudden change in direction and possible risks.[/INST]