I am a little confused about how to construct a force diagram for a suction cup, like a plunger, as it is stuck to a wall. First, I know that the cup is not accelerating, so the gravitational force pulling down on the cup has to be met with an equal but opposite force vector pointing up. However, why would this vector be pulling up? It is stuck to the side of the wall, so wouldn't the suction force be pointing to the side. This is my question.